Question 1

What is the purpose of battery utility testing in backup power systems?

Accepted Answer

Battery utility testing ensures the reliability, health, and performance of backup power systems used in utilities, substations, data centers, and critical infrastructure. Over time, batteries degrade due to factors like temperature, charge-discharge cycles, and age. Testing helps detect early signs of failure such as increased internal resistance, reduced capacity, or imbalance among cells. This enables timely maintenance or replacement, preventing unexpected power loss during outages. Utility testing validates whether batteries meet required discharge durations and ensures compliance with standards like IEEE 450 or IEC 60896. Regular testing minimizes downtime, enhances operational safety, and protects expensive downstream equipment.

KPM provides advanced battery analyzers and constant current discharge kits designed for utility-scale battery banks. These instruments measure internal resistance, voltage, and capacity under load conditions. KPM’s systems are aligned with international testing standards and are used by utilities to perform periodic health checks, identify weak cells, and ensure uninterrupted power backup readiness.

Question 2

1. What is VLF testing, and why is it used for cable diagnostics?

Accepted Answer

VLF (Very Low Frequency) testing applies a low-frequency AC voltage—typically 0.01 Hz to 0.1 Hz—to power cables to assess their insulation condition. It’s used because VLF testing can apply a high voltage stress similar to normal operating conditions but with less heating and damage risk than standard power frequency tests. This makes it ideal for diagnosing medium- and high-voltage cables, especially in field conditions, to detect weaknesses like insulation degradation, voids, or defects before failure occurs.

Question 3

How to Perform a Reliable 10kV Insulation Test?

Accepted Answer

A 10kV insulation resistance test is used to evaluate the dielectric strength of high-voltage equipment like transformers, motors, and cables. To perform it reliably, first de-energize and isolate the equipment, ensuring it's properly grounded. Clean terminals to remove surface contamination.

Connect the insulation tester leads: One to the conductor and the other to ground. Select the 10kV test voltage on the insulation resistance tester. Begin the test and monitor resistance for 1 to 10 minutes—longer durations help identify moisture or insulation defects.

Readings should be in the GΩ (giga ohm) range for healthy insulation. Apply DAR (Dielectric Absorption Ratio) or PI (Polarization Index) analysis to assess insulation aging. Ensure environmental conditions are dry and free of electrical noise for accuracy.

KPM provides high-voltage insulation testers with digital displays, timer functions, and built-in safety features, ensuring accurate, safe, and standards-compliant insulation testing across utility and industrial applications.

Question 4

Qu'est-ce qu'un kit de test de relais ?

Accepted Answer

Un kit de test de relais est un équipement utilisé pour tester différents types de relais. Le kit de test de relais est une combinaison de sources de courant et de tension programmables et d'une minuterie. Pendant le test de relais Le kit de test de relais injecte un défaut dans le relais (sous forme de CT & PT) et mesure le temps de déclenchement ou le temps de réaction du relais. Si le comportement du relais est conforme à ses paramètres, le relais réussit le test, sinon le relais échoue au test.

Question 5

Is SF6 Gas Testing: Health, Safety, and Environmental Implications?

Accepted Answer

Sulfur hexafluoride (SF₆) is widely used as an insulating and arc-quenching gas in high-voltage switchgear due to its excellent dielectric properties. However, SF₆ is a potent greenhouse gas, with a global warming potential over 23,000 times that of CO₂. Hence, rigorous testing and handling are essential for environmental compliance and personnel safety.
Key SF₆ tests include moisture content, purity, and decomposition products (like SO₂ and HF), which help detect gas leakage, contamination, or insulation failure. Exposure to decomposition byproducts can pose health hazards such as respiratory irritation or chemical burns, necessitating strict handling protocols and personal protective equipment (PPE).

KPM offers advanced SF₆ gas analyzers that measure purity, moisture, and decomposition gases in accordance with IEC 60376 and 60480 standards. With portable, user-friendly designs and accurate sensors, KPM’s instruments support safe operation, environmental responsibility, and preventive maintenance of gas-insulated systems.

Question 6

What are the Top 5 PD Testing Techniques – A Quick Comparison?

Accepted Answer

1) Ultrasonic PD Detection

- Detects sound waves from PD events
- Portable, good for on-site inspections
- Limited sensitivity in noisy environments

2) High-Frequency Current Transformer (HFCT)

- Measures high-frequency currents on cables
- Effective for early PD detection
- Requires access to grounding points

3) Transient Earth Voltage (TEV)

- Detects electromagnetic signals from PD inside metal enclosures
- Non-intrusive and widely used in switchgear
- Limited for external PD sources

4) Oscilloscopic PD Measurement

- Directly captures PD pulses using specialized sensors
- Very detailed and accurate
- Requires expert analysis and controlled environment

5) Acoustic Emission (AE) Sensors

- Captures elastic waves from PD activity
- Useful for localizing PD sources
- Can be affected by external noise
- KPM offers advanced PD measurement systems combining multiple techniques for comprehensive, reliable diagnostics.

Question 7

Difference between  Clamp and  Spike Method?

Accepted Answer

Earth Resistance Testing: Clamp vs. Spike Method :

The Clamp Method and the Spike (Fall-of-Potential) Method are two commonly used techniques for measuring earth resistance, each with distinct use cases. The Spike Method (also known as the three-point or fall-of-potential method) is considered the most accurate and is typically used during installation or scheduled maintenance when it’s feasible to disconnect the grounding system. It requires driving two auxiliary spikes into the ground at set distances from the earth electrode and measuring the voltage drop created by a test current. This method provides a true earth resistance value but is time-consuming, invasive, and requires open ground access.

In contrast, the Clamp Method (or Stakeless method) is a quick, non-intrusive test ideal for live systems where disconnecting the earth rod is not possible. Using a special clamp meter, the method induces a test signal and measures current flow through parallel earth paths. It’s convenient and fast but is only applicable when multiple grounding paths exist (e.g., in mesh or grid systems). The Clamp Method does not provide accurate results for isolated earth rods or when there is only a single grounding point.

In summary, the Spike Method is best for accurate baseline testing during commissioning, while the Clamp Method is ideal for routine checks on operational systems without disrupting service.

Question 8

What is the purpose of reference testing in energy meter calibration?

Accepted Answer

The purpose of reference testing in energy meter calibration is to verify and ensure the accuracy of the energy meter by comparing its measurements against a highly precise and traceable standard—called the reference meter or standard. This process identifies any measurement errors or deviations in the energy meter under test, allowing for correction or adjustment to meet specified accuracy classes. Reference testing helps maintain measurement reliability, billing fairness, and compliance with industry standards.

Question 9

How to Test a Li-ion Battery Pack Safely and Efficiently ?

Accepted Answer

Testing a Li-ion battery pack requires a balance of safety, accuracy, and efficiency. Key steps include:

Visual Inspection: Check for swelling, leakage, or damaged terminals.

Voltage Check: Measure open-circuit voltage to ensure cells are within the safe range.

Insulation Resistance Test: Verify electrical isolation between terminals and the battery casing.

Capacity & Discharge Testing: Simulate real-world loads to assess actual capacity, energy output, and discharge efficiency.

Impedance/IR Testing: Identify aging cells or weak connections.

Thermal Monitoring: Monitor temperature rise during charging/discharging to detect potential overheating.

Safety tips include using proper PPE, short-circuit protection, and ventilated areas to avoid thermal events.

KPM's Battery Pack Tester is designed for safe and efficient testing of EV and industrial Li-ion packs. It offers automated test sequences, multi-channel voltage/current monitoring, and integrated thermal protection. The tester's real-time data logging and analysis software help ensure accurate diagnostics, preventive maintenance, and safer battery operation.

Question 10

Why Timing Tests on Circuit Breakers Matters ?

Accepted Answer

During a circuit breaker timing test, the opening and closing times of main and auxiliary contacts are measured to assess the breaker's mechanical and electrical performance. The test simulates real fault or operation conditions, records response times (e.g., O, C, O-C-O), and analyzes contact synchronization, bounce, and trip coil current. These measurements reveal issues like slow operation, wear, or misalignment. Advantages include early fault detection, improved safety, reduced downtime, and compliance with IEC/ANSI standards. KPM offers precise timing test equipment with advanced diagnostics, helping utilities and industries maintain system reliability and extend breaker life through data-driven maintenance planning.

Question 11

What is the purpose of online testing for lightning arresters?

Accepted Answer

The purpose of online testing for HV lightning arresters is to evaluate their health and operational condition while they remain energized and connected to the high-voltage system. This non-intrusive testing monitors critical parameters—especially leakage current—to detect early signs of insulation degradation, moisture ingress, or internal damage. By performing these tests without disconnecting the arrester, utilities can ensure continuous protection against transient over voltages, prevent unexpected failures, and schedule maintenance proactively, thereby enhancing system reliability and safety.

Question 12

What is the use of online partial discharge (PD) monitoring of panels using TEV and contact ultrasonic methods?

Accepted Answer

Online partial discharge monitoring of medium-voltage and high-voltage panels using TEV (Transient Earth Voltage) and contact ultrasonic methods is used to detect and localize internal insulation defects and surface discharges without shutting down the equipment. Here's how each method contributes:

1. TEV (Transient Earth Voltage) Method
Use: Detects internal PD activity, especially within air-insulated switchgear (AIS) and cable terminations inside metal-clad panels.

How it works?
When PD occurs inside enclosed metal-clad gear, it emits fast-rising electromagnetic pulses that induce transient voltages on the metal surfaces. TEV sensors pick up these signals from outside the panel.

Benefit: Non-invasive, detects internal voids, tracking, and corona effects.

2. Contact Ultrasonic Method
Use: Detects surface discharges, such as corona or tracking, which emit high-frequency acoustic signals.

How it works?

A piezoelectric sensor placed on the panel surface detects ultrasonic noise generated by PD activity, even through the enclosure.

Benefit: Helps locate poor insulation, loose connections, or contamination issues causing discharge on the surface.

Combined Use – Why It Matters?
 • Using both TEV and ultrasonic methods together enhances diagnostic accuracy:
 • 
 • TEV gives insight into internal discharge severity and location.
 • 
 • Ultrasonic confirms surface or near-surface PD sources and allows cross-verification.
 • 
 • This dual-method approach is vital for:
 • 
 • Preventive maintenance,
 • 
 • Avoiding insulation failures,
 • 
 • Improving switchgear reliability, and
 • 
 • Extending equipment life without needing shutdowns.

Question 13

Metalworking & Fabrication Machinery :-

Accepted Answer

Top German/European Brands:

• DMG MORI (Germany/Japan) – CNC turning/milling centers .
 • TRUMPF (Germany) – Laser cutting, bending machines .
 • EMAG, INDEX, GILDEMEISTER – Lathes, turn-mill centers .
 • Bystronic (Switzerland) – Sheet metal and laser cutting.
 • Amada (Europe) – Press brakes, punching systems

Question 14

Differences Between 5kV, 10kV, and 15kV Insulation Testers?

Accepted Answer

The main difference between 5kV, 10kV, and 15kV insulation testers lies in their test voltage output, which determines the type of equipment they are suited for and the depth of insulation assessment they provide.

5kV testers are typically used for low to medium voltage equipment like motors, cables, and switchgear up to 25kV.

10kV testers are suitable for higher-voltage systems such as power transformers, HV motors, and cables rated up to 69kV, providing a deeper insulation profile.

15kV testers are used for critical high-voltage assets above 69kV, enabling detection of insulation weaknesses that lower voltages may miss.

Higher voltage testers stress insulation more, revealing latent defects and moisture absorption. However, using too high a voltage on low-rated equipment can cause damage.

KPM offers 5kV, 10kV, and 15kV insulation testers with digital readings, polarization index (PI), and DAR calculations, ideal for field diagnostics and predictive maintenance.

Question 15

How does online testing differ from offline testing of lightning arresters?

Accepted Answer

Online testing of lightning arresters is performed while the arrester is energized and connected to the live high-voltage system. It monitors parameters like leakage current and voltage in real time to assess the arrester’s condition without interrupting power supply or removing the arrester from service.

Offline testing, on the other hand, requires disconnecting the arrester from the system and applying controlled test voltages or impulses in a laboratory or test environment. This allows detailed diagnostic tests, such as insulation resistance, dielectric withstand, and energy absorption capability, but causes downtime and power disruption.

In summary, online testing enables continuous condition monitoring without service interruption, while offline testing offers more comprehensive diagnostics but requires taking the arrester out of operation.

Question 16

2. How does VLF testing differ from conventional AC hipot testing?

Accepted Answer

VLF testing uses a very low frequency (typically 0.01 to 0.1 Hz) AC voltage, whereas conventional AC hipot testing applies standard power frequency (50/60 Hz) voltage. The low frequency in VLF reduces the capacitive charging current in long cables, allowing high test voltages without overheating the cable insulation. This makes VLF safer and more practical for field testing of long medium- and high-voltage cables. In contrast, conventional AC hipot tests can cause excessive heating and damage when used on such cables.

Question 17

What are the Top 5 Mistakes to Avoid While Discharging Lithium-Ion Cells ?

Accepted Answer

Discharging lithium-ion cells must be done with precision to avoid safety risks and performance degradation. Here are the top 5 mistakes to avoid:

1. Over-Discharging Below Safe Voltage Limits: Going below 2.5–3.0V can cause irreversible damage or capacity loss.

2. High Current Discharge Without Monitoring: Excessive current leads to overheating, thermal runaway, or cell swelling. Always follow rated discharge current.

3. Ignoring Cell Balancing: Uneven discharge across cells in a pack can reduce lifespan or cause imbalance-related failures.

4. Lack of Temperature Monitoring: Not monitoring temperature during discharge can hide thermal issues that lead to fires or failure.

5. Discharging Without Load Control or Cut-Off Logic: Manual discharge setups without auto cut-off risk cell damage or safety hazards.

KPM’s Battery Tester prevents these issues through programmable discharge profiles, auto cut-off, real-time voltage/current/temperature monitoring, and cell balancing diagnostics. It ensures safe, accurate discharge testing for EVs, storage systems, and R&D applications.

Question 18

What Is a Dew Point Meter and Why Is It Essential for SF6 Systems?

Accepted Answer

A dew point meter is a device that measures the dew point, the temperature at which air becomes saturated and water vapour condenses into liquid water. In SF6 (sulfur hexafluoride) systems, dew point meters are crucial for monitoring moisture levels, as even small amounts of water can lead to hydrolysis, forming corrosive byproducts like hydrofluoric acid, which damage insulation and metal components. Excess moisture can also reduce the dielectric strength of SF₆, increasing the risk of flashovers and system failures.

Regular dew point monitoring ensures that SF₆ gas remains dry and stable, extending the lifespan of high-voltage equipment like GIS (Gas Insulated Switchgear).

KPM's Dew Point Meters provide fast, accurate, and reliable measurements, with robust sensors designed for field and laboratory use. These meters help utilities maintain safety, reliability, and regulatory compliance, making them an essential part of preventive maintenance in SF₆ systems.

Question 19

What do you understanding AE, HFCT, TEV, and UHF – Which PD Kit Do You Need?

Accepted Answer

Choosing the right Partial Discharge (PD) testing kit depends on your equipment type, accessibility, and testing goals. Here’s a quick comparison:

1. AE – Acoustic Emission
How it works: Detects sound waves from PD using piezoelectric sensors.
Best for: Transformers, bushings, and GIS (localizing PD points).
Pros: Non-invasive, good for pinpointing PD.
Limitations: Sensitive to external noise.

2. HFCT – High-Frequency Current Transformer
How it works: Clamped around the grounding conductor to detect PD pulses.
Best for: Cables, terminations, rotating machines.
Pros: Early detection, non-intrusive.
Limitations: Needs grounding access; less effective in noisy ground systems.

3. TEV – Transient Earth Voltage
How it works: Senses electromagnetic emissions on metal-clad switchgear.
Best for: MV switchgear (metal-enclosed).
Pros: Easy to use, fast screening.
Limitations: Doesn’t work well on non-metallic enclosures.

4. UHF – Ultra High Frequency
How it works: Captures high-frequency EM waves from PD (300 MHz+).
Best for: GIS, gas-insulated transformers, sealed systems.
Pros: Very sensitive and noise-immune.
Limitations: Needs access to UHF sensors or couplers.

Which Kit Do You Need?
For switchgear: TEV + AE
For cables and rotating machines: HFCT
For GIS or sealed systems: UHF + AE
For transformers and bushings: AE + HFCT

KPM offers hybrid PD testing kits combining AE, TEV, HFCT, and UHF sensors for complete diagnostics across all asset types—helping you localize, classify, and trend PD activity efficiently.

Question 20

What safety precautions must be taken during battery testing?

Accepted Answer

Battery testing involves handling high voltages, currents, and hazardous chemicals, so strict safety precautions are essential. Always wear appropriate personal protective equipment (PPE) such as insulated gloves, eye protection, and flame-resistant clothing. Ensure proper ventilation, especially for lead-acid batteries that emit hydrogen gas during charging or discharging. Isolate the battery bank from the load before testing, and use insulated tools to prevent short circuits. Verify polarity before connecting test equipment to avoid damage or sparking. Never allow metal objects near open battery terminals. Maintain safe distances and use warning signs during high-current discharge tests. Monitor temperature rise and terminate testing if overheating or voltage instability is observed. Follow the manufacturer’s guidelines and applicable standards (IEEE, IEC) during every procedure.

KPM’s battery analyzers and discharge testers are equipped with multiple safety features such as overcurrent protection, reverse polarity alarms, thermal cutoffs, and auto-shutdown. KPM also provides user training and safety documentation to ensure proper and secure operation.

Question 21

How to Ensure Compliance With Earth Testing in Renewable Sites?

Accepted Answer

Ensuring Compliance with Earth Testing in Renewable Sites :

To ensure safety and meet regulatory standards in solar, wind, or hybrid renewable energy systems, proper earth resistance testing is essential.

Key Steps:
Follow Standards:
Comply with IEC 60364, IEEE 80, BS 7430, or local codes.

Test Soil Early:
Conduct soil resistivity surveys during design to select the right grounding method.

Use Proper Methods:
Apply the Fall-of-Potential method for commissioning and Clamp Method for periodic checks.

Keep Records:
Log all test data with method, instrument, and environmental details.

Test Regularly:
Schedule annual or biannual resistance tests to catch degradation early.

Use Remote Monitoring (if available):
SCADA or sensors can track resistance levels continuously.

Train Personnel:
Ensure field staff know correct testing procedures and safety protocols.

Third-Party Verification:
For audits or large projects, use certified inspectors for compliance reporting.

Question 22

How is the accuracy class of an energy meter determined during calibration?

Accepted Answer

The accuracy class of an energy meter is determined by evaluating its measurement error under a range of standardized test conditions during calibration. This involves comparing the meter’s energy readings against those of a highly accurate reference standard meter over a set period and at various load levels and power factors.

The calibration process typically tests the meter at multiple points such as:

Light load (e.g., 10% of rated current)

Medium load (e.g., 50% of rated current)

Full load (100% of rated current)

Additionally, measurements are taken at different power factors, including unity (1.0), lagging (inductive), and leading (capacitive) conditions, to simulate real operating scenarios.

At each test point, the percentage error is calculated by comparing the meter’s recorded energy to that of the reference meter. The accuracy class is assigned based on whether these errors stay within the maximum allowable limits defined by standards such as IEC 62053 or ANSI C12.20. For example, a Class 1.0 meter must not exceed ±1% error under these conditions.

Consistent performance across all test points confirms the meter’s accuracy class, ensuring it meets the required precision for billing or monitoring applications.

Question 23

What means measuring contact resistance in Circuit Breakers ?

Accepted Answer

A contact resistance test measures the electrical resistance across closed contacts of a circuit breaker. Low resistance ensures efficient current flow with minimal losses or overheating. High resistance can indicate pitting, corrosion, or poor contact pressure. This test helps detect internal issues not visible externally. It’s essential for preventing energy losses, overheating, and eventual failure during load or fault conditions. Regular testing ensures optimal breaker performance, safety, and longevity. KPM offers contact resistance test equipment with high accuracy and data logging, enabling predictive maintenance, faster troubleshooting, and compliance with IEC/IEEE standards across substations and industrial power systems.

Question 24

Plastic & Rubber Processing Machines :-

Accepted Answer

Top Brands:

• ARBURG (Germany) – Injection moulding.
 • ENGEL (Austria) – Injection moulding.
 • KRAUSSMAFFEI (Germany) – Plastic & rubber machines
 • DEMAG Plastics Group – Injection moulding.
 • BOY (Germany) – Compact moulding machines.

Question 25

Pourquoi les kits de test de relais automatiques sont-ils préférés aux kits de test de relais traditionnels (à base de variac) ?

Accepted Answer

Les kits de test de relais automatiques présentent divers avantages par rapport aux enfants traditionnels
1. Stabilité du signal : la sortie du courant et de la tension de sortie du kit de test de relais automatique n'est pas proportionnelle à son alimentation d'entrée, cela signifie que la sortie de courant et de tension du kit de test de relais est alimentée d'analogique à numérique, puis de conversion numérique à analogique soutenue par un boucle de rétroaction, les signaux de sortie du kit de test de relais ne dépendent donc pas de son alimentation d'entrée. La sortie du kit de test de relais automatique est stable même s'il y a une instabilité mineure dans l'alimentation d'entrée
 
2. Précision, résolution et fonctionnalité : avec les kits de test de relais automatiques, l'utilisateur peut faire varier la fréquence de phase et l'amplitude de tous les signaux de courant et de tension indépendamment avec une résolution et une précision très élevées. Ce n'est pas possible dans les kits d'injection secondaire traditionnels qui peuvent augmenter ou varier uniquement l'amplitude (V ou I) à l'aide d'un variac manuel.

Question 26

Qu'est-ce qu'un kit de test de relais numérique ?

Accepted Answer

Le kit de test de relais numérique est un autre nom pour les kits de test de relais automatiques ou basés sur un microprocesseur. Relais numériques généralement de haute précision qui peuvent être testés avec des kits de test de relais automatiques de haute précision

Question 27

What is principle of detecting PD in Switchgear Using TEV Method ?

Accepted Answer

The Transient Earth Voltage (TEV) method detects partial discharge activity in metal-clad switchgear by capturing fast, high-frequency voltage transients that appear on the internal metal surfaces of the switchgear enclosure.

How It Works:
When partial discharge occurs inside the insulation of live parts (e.g., busbars, bushings), it emits electromagnetic pulses.

These pulses induce high-frequency voltage transients on the inner surface of the switchgear's metal enclosure.

These transients propagate through the metal, eventually reaching the outer surface.

A TEV sensor, placed magnetically or capacitively on the metal surface, detects these transient voltages—typically in the range of MHz frequencies.

Why It Works Well for Switchgear:
Switchgear panels are metal-enclosed, which acts as a waveguide for the transient signals.

TEV signals indicate internal insulation defects like surface tracking, void discharges, or corona inside the equipment.

TEV detection is non-invasive, requires no shutdown, and is widely used for condition-based maintenance.

What TEV Tells You:
Presence of internal PD

Severity of the discharge (by amplitude and repetition rate)

Useful for early detection before insulation failure

KPM’s PD testing kits integrate TEV sensors with digital displays and trending software, making it easy to perform on-site diagnostics of medium-voltage switchgear for early PD detection and risk assessment.

Question 28

Why Cell Balancing is Critical in Battery Pack Design?

Accepted Answer

Cell balancing is essential in lithium-ion battery pack design to ensure uniform voltage levels across all cells, which directly impacts performance, safety, and lifespan. Without balancing, even a single weak or overcharged cell can cause:

Reduced usable capacity

Premature degradation or failure

Overheating or thermal runaway

False full/empty readings during charging/discharging

There are two types:

1. Passive balancing dissipates extra energy as heat and

2. Active balancing redistributes charge to weaker cells, improving efficiency

KPM’s Battery Solution features integrated smart cell balancing technology. It continuously monitors each cell’s voltage and automatically adjusts charge levels to maintain uniformity. Whether in EVs, solar storage, or industrial packs, KPM’s system ensures balanced charging/discharging, enhanced cycle life, and optimal safety. The real-time monitoring interface also provides visual alerts on imbalance conditions—enabling proactive maintenance and higher reliability.

Question 29

What is Karl Fischer Titration ? Explain Moisture Testing in Oil.

Accepted Answer

Karl Fischer (KF) titration is a precise chemical method used to measure moisture content (water) in substances, including insulating oils, with accuracy down to parts per million (ppm). It's the preferred method for transformer oil and lubricants because even trace moisture can degrade dielectric strength, cause corrosion, or affect equipment performance.

How It Works:
KF titration is based on a chemical reaction where iodine reacts with water in the presence of sulfur dioxide and alcohol, using a base (often imidazole or pyridine) as a catalyst:

This reaction occurs until all water is consumed. The amount of iodine used is directly proportional to the moisture present.

Types of KF Titration:
Volumetric KF: For water content above 1%. Common in oil testing.

Coulometric KF: For ultra-low moisture (<1%), generating iodine electrochemically.

Advantages:
Highly accurate (1–10 ppm range).

Specific to water (no interference from other volatiles).

Widely accepted in ASTM D1533 for transformer oil testing.

KPM supplies Karl Fischer titrators for both volumetric and coulometric methods, used in power utilities and oil testing labs to ensure insulation oils remain within safe moisture limits.

Question 30

What is the use of both side ground feature in contact resistance meter ?

Accepted Answer

The both-side ground feature in a contact resistance meter allows the tester to connect the instrument’s ground reference on both ends of the circuit breaker contacts simultaneously. 
For Example:-

- Eliminate interference and noise caused by stray currents or electromagnetic fields.
- Improve measurement accuracy by ensuring a stable, low-resistance ground path.
- Prevent false readings that may occur if only one side is grounded.
- It increases the safety of the operation.
- KPM’s contact resistance meter CRT 200 G  use this feature to deliver precise, repeatable readings critical for assessing contact health and ensuring reliable breaker operation.

Question 31

What will be seasonal Impact on Ground Resistance Measurements?

Accepted Answer

Seasonal Impact on Ground Resistance Measurements
Ground resistance values can vary significantly with seasonal changes due to environmental factors affecting soil conditions:

Soil Moisture:
During wet seasons (rainy or winter), soil moisture increases, lowering ground resistance by improving conductivity. Conversely, dry seasons cause soil to dry out, increasing resistance.

Soil Temperature:
Colder temperatures can increase soil resistivity as water in soil may freeze, reducing conductivity. Warmer temperatures generally improve conductivity.

Soil Composition Changes:
Seasonal changes in organic matter decomposition and salt concentration may also affect soil resistivity.

Vegetation and Ground Cover:
Plant growth during certain seasons can affect soil moisture retention and contact with grounding electrodes.

Implications
Testing during different seasons may yield varying results; hence, baseline measurements should be taken in both dry and wet conditions to understand worst-case scenarios.

For accurate monitoring and compliance, schedule tests consistently or adjust acceptable resistance thresholds based on seasonal variation.

Question 32

Printing & Packaging Machinery :-

Accepted Answer

Top Brands:

• HEIDELBERG (Germany) – Offset printing
 • KBA (Koenig & Bauer) – Sheetfed & web printing
 • BOBST (Switzerland) – Die cutting, folder-gluers
 • Windmöller & Hölscher (W&H) – Flexographic printing
 • MAN Roland – Newspaper and offset printing

Question 33

What is PQ analyzer , how it is different than Power recorders ?

Accepted Answer

A Power Quality Analyzer and a Power Recorder may appear similar at first glance, but they serve distinct purposes in electrical diagnostics and monitoring. A Power Quality Analyzer is specifically designed to detect, analyze, and troubleshoot disturbances in the power system such as voltage sags, swells, transients, harmonics, flicker, unbalance, and frequency deviations. These analyzers are equipped with high-speed sampling capabilities, waveform capture, and harmonic spectrum analysis tools, making them ideal for identifying and resolving issues that can affect the performance or lifespan of sensitive electrical equipment. They are also commonly used for compliance monitoring against standards like EN 50160 or IEEE 519.

In contrast, a Power Recorder is primarily used for long-term logging of power parameters such as voltage, current, power (kW, kVA, kVAR), and energy consumption. Its focus is more on load studies, energy audits, and identifying usage patterns over time rather than real-time disturbances or quality issues. Power Recorders usually measure and log RMS values at set intervals and are not typically equipped to detect fast transients, harmonics, or waveform-level events.

While some overlap exists—many modern Power Quality Analyzers also offer recording functionality—the key difference lies in the depth of analysis. A Power Quality Analyzer is a diagnostic tool used when there’s a suspected problem or for verifying power quality compliance, whereas a Power Recorder is more of a monitoring tool for tracking energy use and system loading trends over time.

Question 34

How does internal resistance measurement indicate battery health?

Accepted Answer

Internal resistance (IR) is the opposition a battery offers to current flow within its own structure. As batteries age or degrade, their internal resistance increases due to chemical wear, sulfation (in lead-acid), or electrode deterioration.

Here's how it reflects battery health:

Low IR = Healthy battery: Indicates good electrolyte condition, intact electrodes, and low energy loss during discharge.

High IR = Degraded battery: Results in voltage drops under load, reduced capacity, and heat generation during operation.

Rising IR over time signals aging or developing faults, even if voltage appears normal.

Sudden spikes in IR may indicate failing cells or poor interconnections.

Thus, internal resistance is a quick, non-invasive diagnostic metric used to identify weak or failing batteries before they cause critical power failures.

KPM’s battery analyzers measure IR accurately across large battery banks, providing real-time indicators of cell health and enabling predictive maintenance.

Question 35

Do you know the common standards and regulations followed for energy meter calibration?

Accepted Answer

What are the common standards and regulations followed for energy meter calibration?

Energy meter calibration is governed by international and regional standards to ensure accuracy, reliability, and uniformity. The most widely followed standards include:

IEC 62053 series: International standards specifying performance and accuracy requirements for different classes of electricity meters (e.g., IEC 62053-21 for static meters, IEC 62053-22 for active energy meters, and IEC 62053-23 for reactive energy meters).

IEC 60521 and IEC 60522: Standards covering calibration methods and testing procedures for electric meters.

ANSI C12 series: North American standards, such as ANSI C12.20, that define accuracy classes and testing protocols for electric meters.

OIML R46: International recommendation by the International Organization of Legal Metrology outlining accuracy requirements and test procedures for electricity meters used in billing.

National regulations: Many countries have their own legal metrology regulations and certification requirements to ensure meters used for billing comply with local laws.

Question 36

3. What types of cable defects can VLF testing detect?

Accepted Answer

VLF testing is effective at identifying a wide range of insulation defects and weaknesses within medium- and high-voltage power cables. It can detect partial discharge (PD) activity, which is a common early indicator of insulation deterioration such as microscopic voids or cracks within the cable’s insulation material. These PD sites generate localized electrical discharges that degrade the insulation over time, potentially leading to catastrophic failure if not addressed.

Additionally, VLF testing can reveal water ingress problems, where moisture penetrates the insulation and lowers its dielectric strength, as well as contamination or aging effects such as thermal, mechanical, or chemical degradation of the insulation material. It can also uncover manufacturing defects like thin spots, improper curing, or insulation gaps.

While VLF testing is excellent for assessing the overall integrity of the cable insulation and detecting areas of weakness, it may not precisely locate the defects. For detailed localization, it is often combined with other techniques such as partial discharge (PD) measurements or time-domain reflectometry (TDR).

Question 37

What parameters are measured during online testing of lightning arresters?

Accepted Answer

During online testing of lightning arresters, the key parameters measured include:

Leakage current: Both resistive and capacitive components are monitored to detect insulation deterioration or moisture ingress.

Discharge current: Measures the arrester’s response to transient overvoltages.

Voltage across the arrester: To correlate leakage current with operating voltage.

Power factor (dissipation factor): Indicates the level of insulation losses and ageing.

Harmonic content of leakage current: Helps identify partial discharges or defects.

Continuous monitoring of these parameters helps identify early signs of failure and evaluate arrester condition in real time.

Question 38

What are the key parameters measured by a battery analyzer?

Accepted Answer

A battery analyzer is used to assess the condition and performance of individual cells and complete battery banks. The key parameters it typically measures include:
Internal Resistance (IR):Indicates the battery’s ability to deliver current. Higher resistance means deterioration or aging.

Voltage (V):
Measures the open-circuit voltage of each cell or unit to check state-of-charge and overall health.

Conductance (optional):
Used as an alternative to resistance in some analyzers to determine battery condition.

Temperature (°C):
Affects performance and safety. Monitoring ensures accurate readings and helps prevent overheating.

State of Health (SoH):
Some analyzers estimate the health of the battery based on historical and real-time data.

Cell Imbalance:
Detects inconsistencies among cells in a battery bank, which can lead to system failure.

Ripple Voltage (if applicable):
Monitors AC noise on DC lines, often in UPS and telecom systems.

KPM’s battery analyzers measure all key parameters—internal resistance, voltage, temperature, and cell imbalance—with high accuracy. Features include: High-precision sensors and rugged design for utility environments, Built-in safety features (reverse polarity, overvoltage alerts), PC software for data logging, trending, and report generation.
Widely used in substations, power plants, and telecom towers for preventive maintenance and health diagnostics.

Question 39

What types of leakage current patterns indicate a failing arrester?

Accepted Answer

In surge arresters (typically metal oxide varistor or MOV-based), leakage current patterns can offer early warning signs of deterioration or failure. Here are the key types of leakage current patterns that indicate a failing arrester:

1. Increasing Total Leakage Current Over Time
What it means: The arrester is gradually losing its insulation resistance.

Cause: Ageing of the zinc oxide blocks or moisture ingress.

Warning: A consistent upward trend is a red flag — especially under normal system voltage.

2. High Resistive Leakage Current
What it means: An increase in resistive (non-linear) current indicates internal degradation.

Why it's critical: Unlike capacitive leakage (which is normal), resistive leakage is a sign of arrester deterioration.

How it shows up: Measured using third-harmonic analysis or waveform separation techniques.

3. Sudden Jumps or Spikes in Leakage Current
What it means: Possible internal flashover, moisture ingress, or external contamination.

Typical sign: A sharp increase without a gradual trend.

Next step: Immediate inspection or replacement is usually advised.

4. Leakage Current with Strong Daily Variation
What it means: Leakage current rises during daytime due to heating and falls at night — abnormal if variation is large.

Potential cause: Moisture or contamination interacting with thermal cycles.

5. Phase Shift Changes in Leakage Current
What it means: The phase angle between voltage and leakage current shifts — especially the third harmonic.

Used in: Online monitoring systems.

Why it matters: Indicates the balance between capacitive and resistive components is shifting unfavourably.

6. Leakage Current under Wet Conditions
What it means: If leakage current increases dramatically during rain or fog, it may indicate surface tracking or contamination.

Action: Cleaning or replacing the arrester may be required.

Question 40

Do you know which equipment is used as a reference standard during energy meter calibration?

Accepted Answer

The reference standard in energy meter calibration is a highly accurate and traceable device known as a calibration standard meter or reference meter. This equipment has a much higher precision than the meter under test, typically with an accuracy class of 0.02% or better. Common types include:

Standard reference meters: Precision static energy meters designed specifically for calibration, with traceability to national or international measurement standards.

Calibrated instrument transformers: High-accuracy current and voltage transformers to supply accurate test signals.

Precision power sources: Devices that can generate stable and controllable voltage and current at various loads and power factors to simulate real operating conditions.

Calibration benches or test rigs: Integrated setups that combine the above equipment to perform automated, controlled calibration tests.

Using these reference standards ensures that the energy meter calibration is accurate, repeatable, and compliant with metrology requirements.

Question 41

4. What is Tan Delta (VLD) testing, and how does it assess cable insulation quality?

Accepted Answer

Tan Delta (also called Very Low Dissipation factor or VLD) testing measures the dielectric losses in cable insulation by applying an AC voltage and analyzing the phase difference between the current and voltage. The "tan delta" represents the ratio of resistive (lossy) current to capacitive (ideal) current. A low tan delta value indicates good insulation with minimal energy loss, while higher values suggest deterioration due to moisture, contamination, or aging.

By measuring these losses, Tan Delta testing assesses the overall insulation condition and detects early-stage degradation before catastrophic failure. It is highly sensitive to insulation quality changes and is commonly used for condition assessment and preventive maintenance of medium- and high-voltage cables.

Question 42

How Harmonics Affect Transformer Performance?

Accepted Answer

Effects of Harmonics on Transformer Performance
Increased Heating (Core and Copper Losses):
Harmonics cause additional eddy current and hysteresis losses in the transformer core and I²R losses in the windings due to the skin effect and proximity effect. This leads to excessive heating, even when the transformer is operating within its rated current. This can reduce transformer lifespan or even cause thermal failure.

Reduced Efficiency:
As harmonic losses increase, the overall efficiency of the transformer drops. It may appear to be operating under normal conditions in terms of RMS values, but real power losses are higher.

Derating of Transformer:
To compensate for the increased losses due to harmonics, transformers are often derated (i.e., used at less than their nameplate capacity) when supplying non-linear loads. IEEE Std C57.110 provides guidelines for calculating the required derating.

Increased Vibration and Noise:
Harmonics can cause magnetostriction effects in the transformer core, resulting in audible noise and mechanical vibration, which can be especially problematic in sensitive environments.

Insulation Stress and Aging:
Repeated thermal cycling due to harmonic-induced heating stresses the insulation system, accelerating insulation degradation and reducing transformer life expectancy.

Neutral Overload (in 3-phase systems):
In systems with significant triplen harmonics (3rd, 9th, 15th...), these components add arithmetically in the neutral conductor. This can cause the neutral to overheat, even if the phase conductors are within limits.

Incorrect Protective Relay Operation:
Harmonic distortion can interfere with current and voltage sensing used in protective relays, leading to nuisance tripping or failure to trip during faults.

Question 43

Pharmaceutical, Chemical & Process Equipment :-

Accepted Answer

Top Brands:

• Glatt (Germany) – Fluid bed systems, granulators
 • GEA (Germany) – Process engineering, mixers
 • FETTE (Germany) – Tablet presses
 • IMA (Italy) – Packaging & pharma lines
 • Hosokawa Alpine (Germany) – Powder & particle processing

Question 44

Qu'est-ce qu'un kit de test de relais universel ?

Accepted Answer

Le kit de test de relais universel est un autre nom pour les kits de test de relais automatiques car l'utilisateur peut faire varier la phase, la fréquence et l'amplitude des sources de courant et de tension indépendamment et générer tout type de défaut.

Question 45

Why is understanding Coil Current Analysis in Breaker Testing important ?

Accepted Answer

Coil current analysis involves measuring the current drawn by the trip and close coils during circuit breaker operation. This current signature helps diagnose the breaker’s mechanical and electrical health. Changes in current shape, peak value, or duration can reveal issues like sluggish movement, coil burnout, weak springs, or mechanical obstructions.

Analyzing the coil current curve provides early warnings of potential failure before timing or contact issues become visible. It enhances predictive maintenance and helps avoid costly downtime.

KPM’s test systems capture detailed coil current waveforms, enabling precise diagnostics, improved reliability, and safe operation of critical power systems.

Question 46

How AH Curve Tracers Improve Battery Quality Analysis?

Accepted Answer

Ampere-Hour (AH) Curve Tracers or constant current discharge testers are critical tools for evaluating battery quality. By discharging the battery at a fixed current and recording voltage over time, they generate AH curves that reveal:

1. Actual capacity vs. rated capacity

2. Voltage stability during load

3. Internal resistance and aging behavior

4. Cut-off voltage performance

5. Cell degradation patterns over cycles

This data helps manufacturers and maintenance teams identify underperforming cells, confirm batch consistency, and detect early signs of capacity fade—essential for EVs, energy storage, and critical backup systems.

KPM’s Constant Current Battery Testing Equipment is designed for precise AH curve analysis. It offers programmable discharge rates, real-time voltage monitoring, and auto cut-off features. With multi-channel support and detailed data logging, it enables accurate grading, performance benchmarking, and lifecycle testing—ensuring battery packs meet safety and performance standards before deployment.

Question 47

How to Identify Oil Contamination Using BDV Testers?

Accepted Answer

Breakdown Voltage (BDV) testing is a key method to identify contamination in insulating oils used in transformers, circuit breakers, and other high-voltage equipment. A BDV tester applies a gradually increasing AC voltage to a sample of insulating oil placed between two standard electrodes. Clean, dry oil has high dielectric strength and resists electrical breakdown. However, the presence of moisture, dissolved gases, carbon particles, or sludge lowers the breakdown voltage significantly.

Typically, good transformer oil should withstand 30 kV or more in a 2.5 mm electrode gap. A low BDV reading (e.g., below 20 kV) suggests contamination. Multiple test cycles (usually 5–6) help eliminate anomalies and confirm consistency.

KPM provides automated and manual BDV testers with features like automatic voltage ramping, stirrers for even testing, digital displays, and built-in standards (IEC 60156, ASTM D1816), ensuring accurate detection of oil contamination and timely maintenance planning.

Question 48

What are the Diagnosing Cable Defects With HFCT-Based PD Testing ?

Accepted Answer

High-Frequency Current Transformer (HFCT) sensors are widely used for detecting and diagnosing partial discharge (PD) activity in power cables. They are clamped around the earth (ground) conductor to sense high-frequency current pulses generated by insulation defects.

How HFCT PD Testing Works:
PD Activity Inside Cable Insulation:
Voids, cracks, or deteriorated insulation cause small electrical discharges.

Pulse Propagation:
These discharges generate high-frequency current pulses (MHz range) that flow along the grounding system.

HFCT Sensor Detection:
The HFCT sensor detects these pulses non-invasively by clamping it around the cable’s earth conductor without disconnecting the system.

Signal Analysis:
The captured pulses are analyzed for:

Pulse shape and repetition rate

Time-of-flight (for PD location)

Amplitude and phase-resolved patterns (PRPD)

What It Diagnoses:
Defects in cable joints, terminations, insulation

Water trees or aging in XLPE cables

Internal corona or tracking activity

Advantages of HFCT PD Testing:
Online or offline testing possible

Non-intrusive and safe

Early detection prevents costly cable failures
Can be used with multiple sensors for PD location (triangulation)

KPM’s HFCT-based PD testing solutions are designed for rapid setup, high sensitivity, and advanced diagnostics—enabling utilities and industries to monitor cable health with confidence.

Question 49

What are Real-World Applications of PQ Recorders?

Accepted Answer

Real-World Applications of Power Quality (PQ) Recorders
1. Load Profiling and Energy Audits
PQ recorders are commonly used to monitor energy consumption patterns over time. This helps identify peak demand periods, base loads, and inefficiencies, supporting energy optimization and cost savings.

2. Electrical System Commissioning
During commissioning of new installations—such as switchboards, transformers, or generators—PQ recorders verify voltage levels, current balance, and overall system performance to ensure proper operation.

3. Capacity Planning and Expansion
Before adding new electrical loads, PQ recorders assess whether existing infrastructure can support the additional demand. This prevents overloading and supports informed upgrade decisions.

4. Renewable Energy Integration
In solar and wind power systems, PQ recorders monitor output stability, voltage, and frequency to ensure grid compliance and smooth integration with the main supply.

5. Troubleshooting Intermittent Issues
When power issues such as flickering, nuisance tripping, or undervoltage occur, PQ recorders help log and analyze events that may not be immediately visible during spot checks.

6. Utility Billing Verification
PQ recorders provide accurate data for verifying utility charges, particularly demand-based billing and power factor penalties, helping avoid disputes or overcharges.

7. Temporary Power Monitoring
For construction sites, events, or mobile power setups, PQ recorders ensure temporary supplies are stable, safe, and suitable for operational requirements.

8. Preventive Maintenance and Trend Analysis
Long-term monitoring enables early detection of issues like increasing unbalance or loading trends, allowing for proactive maintenance before failures occur.

Question 50

How do environmental conditions affect energy meter calibration results?

Accepted Answer

Environmental factors like temperature, humidity, and atmospheric pressure can influence the accuracy of energy meter calibration.

Temperature: Changes in temperature can affect the electrical characteristics of meter components, causing measurement drift or errors. Most calibration standards specify temperature ranges within which tests should be performed to ensure consistency.

Humidity: High humidity can cause condensation or moisture ingress, impacting insulation resistance and electronic circuits, leading to inaccurate readings during calibration.

Atmospheric pressure: Variations in pressure can subtly affect electrical properties, especially in sensitive equipment, although its impact is generally less significant than temperature or humidity.

To minimize these effects, calibrations are ideally conducted in controlled laboratory environments with stable temperature and humidity, or environmental conditions are recorded and accounted for in the calibration report.

Question 51

Which standard is most widely accepted worldwide?

Question 52

How to do Dynamic Contact Travel Analysis ?

Question 53

Qu'est-ce que le kit de test de relais 6 phases, lorsqu'il n'y a que 3 phases CT ou PT dans le système d'alimentation ?"

Question 54

What is UHF PD Testing in GIS – High Sensitivity Explained?

Question 55

Woodworking Machines :-

Question 56

What do you mean by Preventing Battery Fires also what are the Role of Air Leakage Testers ?

Question 57

What is Viscosity and Pour Point in Transformer Oils?

Question 58

Can battery conductivity testing detect early-stage cell degradation ?

Question 59

5. How do Tan Delta results indicate the health or degradation of a cable?

Question 60

What are the Benefits of 24/7 Power Quality Monitoring?

Question 61

Why is constant current discharge testing crucial in critical power applications?

Question 62

6. What is VLF Partial Discharge (PD) testing, and how does it help's identify insulation defects?

Question 63

What is Flash Point Testing? What are its Safety Standards and Applications?

Question 64

Quel est le besoin d'un logiciel avancé avec les kits de test de relais automatiques ?

Foire aux questions (FAQ)

Kits de test de relais

Analyseurs CT/PT

Testeurs LA

TTR , Transformateur tourne Ratio

TWRT (testeur de résistance d'enroulement de transformateur)

Tan delta

Test de décharge partielle (portable)

Test d'huile de transformateur

Caméras thermiques

Panalyseur de qualité

Testeurs d'isolement de diagnostic

Kits d'injection primaire

Hipots ( AC / DC / VLF )

Testeurs de terre à pince

Testeurs de terre (méthode Spike)

Références de test de compteur d'énergie - 3 ph et 1 ph

Test de décharge partielle - applications de laboratoire

Test de batterie (utilitaire)

Test de batterie (EV & Lab)