KPM Penta PD FAQ

The KPM Penta PD is a handheld partial discharge (PD) tester for checking the insulation condition of high-voltage equipment while it stays in service.The host has two sensors built into its front end: a transient earth voltage (TEV) sensor and an airborne ultrasonic sensor. Those two cover high- and low-voltage switchgear on their own. For transformers, GIS, cables and overhead lines you plug an external sensor into the port at the bottom, and the host switches its measuring mode automatically.For every measurement it shows a time-domain waveform, a PRPD map and a PRPS pattern, counts discharge pulses per power cycle, and gives an automatic diagnosis of the likely discharge type. The host weighs 0.4 kg, has a 4-inch colour touch screen and runs about 6 hours on its internal battery.Picture filepenta-pd-partial-discharge-tester-host-layout.pngAlt textKPM Penta PD handheld partial discharge tester showing built-in sensor, power button, display and extension interfaceCaptionThe Penta PD host: built-in sensor at the top, display and menu keys in the middle, sensor extension port at the bottom.

The manual lists these applications:•     High-voltage switchgear and ring main units (RMUs)•     Current and voltage transformers•     Power transformers, including dry-type transformers•     Gas-insulated switchgear (GIS)•     Power cables, cable terminations and cable branch boxes•     Overhead lines and insulators•     Motors, using the contact ultrasonic sensorIt is used by power generation and distribution companies, railway systems, petrochemical plants' power supply systems and in aerospace testing. The built-in sensors handle switchgear; each of the other equipment types needs the matching external sensor (see the sensor question in this section).

No. The Penta PD uses non-intrusive detection. The equipment stays energised and in normal service, and you do not need a separate high-voltage test source. That makes it more convenient to use than a traditional pulsed partial discharge detector.

Standard supply:•     Detection host with built-in TEV and ultrasonic sensors•     Charger•     USB cable (charging and PC data transfer)•     Manual•     Ex-factory inspection report•     Certificate of conformity•     Warranty cardOptional items:•     External contact ultrasonic sensor (transformers, GIS, motors)•     High-frequency current transformer, HFCT (cables)•     UHF sensor (GIS)•     External non-contact ultrasonic wave concentrator (overhead lines)•     Flexible ultrasonic sensor (switchgear)•     Earphones•     Test lead setWi-Fi data transfer is also an optional function. Confirm with KPM which options are in your order.

Match the sensor to the equipment:•     Switchgear and RMUs: the built-in TEV and ultrasonic sensors. The optional flexible ultrasonic sensor (40 kHz) reaches awkward gaps.•     Power transformers and motors: the contact ultrasonic sensor (40–150 kHz), placed on the tank.•     GIS: the UHF sensor (300–3000 MHz) at insulating basins and observation windows, plus the contact ultrasonic sensor on the tank.•     Power cables: the HFCT (3–30 MHz), clamped on the cable's earthing lead.•     Overhead lines and insulators: the ultrasonic wave concentrator (40–200 kHz), aimed from the ground.All external sensors use the same port on the host.Picture filepd-ultrasonic-wave-concentrator-overhead-line.pngAlt textUltrasonic wave concentrator sensor for overhead line partial discharge detectionCaptionThe ultrasonic wave concentrator, one of five optional external sensors.

Yes. Every external sensor connects through the same multi-function sensor port at the bottom of the host. Each sensor carries an ID; the host reads it, selects the sampling channel for that sensor's frequency band and shows the sensor model and frequency at the top of the screen.The host normally switches mode by itself. It has four channels of different frequencies integrated behind that one port, which is what lets one instrument cover switchgear, transformers, GIS, cables and overhead lines.Picture filepenta-pd-sensor-expansion-port-usb-sd-earphone.pngAlt textBottom of the Penta PD host showing USB charging port, SD card slot, earphone jack and sensor interfaceCaptionBottom panel: USB/charging, SD card, earphones and the multi-function sensor interface.

When a partial discharge occurs inside metal-clad switchgear, it emits an electromagnetic wave. The metal enclosure blocks most of it, but a small part escapes through joints and gaskets and induces a short voltage pulse on the outside surface of the enclosure. That pulse is the transient earth voltage, also called the ground wave. It ranges from a few millivolts to a few volts with a rise time of a few nanoseconds.The Penta PD has a capacitive TEV sensor built into the front of the host, working from 3 to 100 MHz. To measure, you hold the front of the host flat against the metal surface of the panel, with nothing between the instrument and the metal. Readings are in dBmV, from 0 to 60 dBmV.Picture filetev-sensor-held-flat-on-switchgear-metal-surface.jpgAlt textPenta PD built-in TEV sensor held flat against the metal surface of a switchgear panelCaptionTEV test: the front of the host held flat on the panel's metal surface.

A discharge heats the gas around it in an instant. The gas expands, then cools and contracts, and that sends out sound waves across a wide band. The part above 20 kHz is ultrasonic and cannot be heard directly. Because the discharge area is small, the sound source is the discharge point itself.The Penta PD measures ultrasound in two ways:•     Airborne: the built-in sensor (centred on 40 kHz) and the flexible sensor pick up sound that leaves switchgear through the gaps in the panel, so you hold the sensor at a gap.•     Contact: the external contact sensor sits on a transformer tank or GIS enclosure and picks up sound travelling through the metal.With earphones connected, the instrument converts the ultrasonic signal into audible sound so you can listen to the discharge.Picture filepenta-pd-built-in-ultrasonic-and-tev-sensors.pngAlt textFront end of the Penta PD host showing the built-in ultrasonic sensor and built-in TEV sensorCaptionFront of the host: built-in ultrasonic sensor (left) and built-in TEV sensor (right).

Insulation in GIS and other high-voltage equipment has a very high breakdown strength. When a discharge happens in a very small space there, the current pulse is extremely steep, with a rise time under 1 nanosecond, and it radiates electromagnetic waves up to several gigahertz.UHF detection picks up that radiation from 300 MHz into the gigahertz range. Two things make it well suited to GIS:•     Corona interference in a substation is mostly below 300 MHz, so a UHF sensor ignores much of it and has high sensitivity and good immunity to noise.•     The metal GIS tank blocks the signal, but some leaks out through the insulating basins and observation windows. Placing the sensor there catches it.UHF results are analysed with the PRPD and PRPS patterns described in section E.Picture fileuhf-partial-discharge-detection-principle-gis.pngAlt textDiagram of UHF partial discharge detection in GIS with an external sensor at the basin insulatorCaptionUHF principle: the signal leaks out through the basin insulator, where the external sensor picks it up.

A high-frequency current transformer (HFCT) is a clamp-on sensor for high-frequency pulse currents.Power cables have metal armour and screens, so the ultrasonic and high-frequency signals from a discharge inside the cable cannot be picked up from the outer layer. The discharge does, however, send a pulse current along the cable screen and down its earthing lead to the substation earth. The HFCT clamps around that earthing lead or the earthed outer sheath and measures the pulse.Penta PD HFCT figures: 3–30 MHz detection band, transfer impedance 9.9 mV/mA, sensitivity 1 mV, detection range 0–10,000 mV. HFCT readings are in millivolts.Picture filehfct-wiring-on-cable-earth-lead.pngAlt textHFCT sensor clamped around the earthing wire of a high-voltage cable to detect partial discharge pulse currentCaptionThe HFCT clamps around the cable's earthing lead, where the discharge pulse current flows to earth.

None is best everywhere. Each detects a different signal, so the right one depends on the equipment and on how the signal gets out:•     Switchgear: use TEV and ultrasonic together. Ultrasound needs an air gap to escape through; TEV needs a metal surface.•     Transformers: contact ultrasonic on the tank.•     GIS: UHF at the insulating basins, with contact ultrasonic on the tank.•     Cables: HFCT on the earthing lead.•     Overhead lines: the ultrasonic wave concentrator.The two switchgear methods also suffer from different interference. Ultrasonic interference stays local: flashing fluorescent lamps, ultrasonic pest repellers, running fans. TEV interference is radio frequency and fills the whole space: welding machines, frequency converters (VFDs), walkie-talkies and broadcast transmitters. When one method is swamped by noise, the manual's advice is to switch to the other.

Both plot discharge pulses against the phase of the power-frequency voltage, because different defects discharge at different points in the voltage cycle.•     PRPD (phase-resolved partial discharge) is a two-dimensional map of amplitude against phase angle, 0° to 360°. Pulses from many cycles build up on one chart, so a repeating discharge shows as clusters at fixed phase positions.•     PRPS (phase-resolved pulse sequence) is a three-dimensional pattern of amplitude, phase and time, one row per cycle. It shows how the discharge behaves from cycle to cycle.Used together, they let you judge whether a signal is a real discharge and what kind of defect it is likely to be. Section E shows typical patterns for each discharge type.Picture fileprpd-and-prps-partial-discharge-patterns.pngAlt textPenta PD screen showing a PRPD map above a three-dimensional PRPS patternCaptionPRPD map (top) and PRPS pattern (bottom) from the same measurement.

Partial discharge signals range over several orders of magnitude, so they are shown on a logarithmic decibel scale:•     Ultrasonic readings are in dBµV, relative to 1 µV. The Penta PD range is −6 to 68 dBµV.•     TEV and UHF readings are in dBmV, relative to 1 mV. Range 0–60 dBmV.•     HFCT readings are in millivolts.A negative dBµV value does not mean a negative signal. It means the signal is smaller than 1 µV; the more negative, the closer to zero. In a quiet environment without interference, ultrasonic readings usually sit between −6 and 0 dBµV.

It is the number of discharge pulses detected in one power-frequency cycle, which is 20 ms on a 50 Hz system. The Penta PD shows it on the test screen and can count up to 1,400 pulses per cycle on the TEV channel.The manual uses it together with amplitude when judging TEV results: high-amplitude readings with fewer than 50 pulses per cycle are typical of a real discharge

1.     Switch on. The built-in ultrasonic sensor is selected by default; touch the sensor area at the top left of the screen to change to TEV.2.     Measure the background first (see the background question below). If it is high, find and remove the source before testing.3.     Ultrasonic: hold the sensor at a gap in the panel. TEV: hold the front of the host flat on the panel's metal surface.4.     Keep the instrument still for 2–3 seconds until the reading is steady.5.     Press Save. Keep the host in place until the progress bar finishes, so the PRPD and PRPS patterns are built from a valid signal.6.     Compare the panel value with the background and judge it against the reference tables in this section.7.     Repeat at several points on each panel.Name each saved file with the actual panel number so results can be traced later.Picture filetev-partial-discharge-test-on-switchgear-panel.jpgAlt textEngineer holding the Penta PD partial discharge tester against a switchgear panelCaptionSwitchgear test with the built-in sensors.

For a middle panel in a line-up, measure at:•     front middle and front lower•     rear upper, rear middle and rear lowerFor the panels at each end of the line-up, add the side upper, side middle and side lower positions.For TEV, the point must be on the metal surface of the panel, with nothing between the instrument and the metal. For ultrasonic, use the door gaps and seams at those positions, because the sound leaves the panel through gaps.Picture fileswitchgear-partial-discharge-measuring-points.pngAlt textDiagram of recommended TEV and ultrasonic partial discharge measuring points on a switchgear panelCaptionRecommended measuring points on the front, rear and side of a panel.

Every reading is judged against the background, so a high background can hide a real discharge or create a false one.•     Ultrasonic background: aim the instrument at the air 2–3 metres from the switchgear and hold it still for a while. If the background is above about 10 dBµV, remove the interference first; otherwise it masks the real signal. If you cannot remove it, use TEV instead.•     TEV background: hold the sensor against a metal object that is not earthed, such as a metal plate or door frame, and note the reading. A TEV background above 20 dB may hide discharge in the panel, so find and remove the source before retesting.Record the background with every set of results.

Compare the panel reading with the background, then use the manual's reference table:•     Below 6 dB: no partial discharge•     6 to 15 dB: the equipment may have slight partial discharge•     Above 15 dB: serious dischargeWhen a reading is above 6 dB, combine it with a TEV measurement before deciding.The dividing line between "none" and "slight" differs a little between utilities; some use 6 dBµV and some use 8 dBµV. The manual recommends 6 dBµV because it gives earlier warning. If your utility or client has its own threshold, use theirs.

The manual's TEV reference table, with the action for each band:•     Background above 20 dB: high noise may hide discharge in the panel. Remove external interference and retest.•     All panel readings and the background below 20 dB: no partial discharge. Check again in a year.•     Panel reading 20–29 dB above background: slight partial discharge.•     29–40 dB: medium partial discharge. Report it and shorten the inspection interval.•     40–50 dB: serious partial discharge. Report it, shorten the interval and find the source at the next outage.•     50–60 dB: serious partial discharge. Report it, shorten the interval and take the equipment out of service for repair as soon as possible.Limits differ slightly between regions, but not by much. Look at the PRPD pattern and pulse count as well as the number.

The manual names these interference sources:•     Ultrasonic: flashing fluorescent lamps, ultrasonic mouse and pest repellers, running fans.•     TEV: welding machines, frequency converters (VFDs), walkie-talkies and radio or broadcast transmitters.To keep them out of your results:•     Measure the background first and remove sources you can switch off.•     If ultrasonic noise cannot be removed, use TEV, and the other way round.•     Look at the waveform: noise has similar amplitude across the whole phase range; discharge shows a few prominent pulses at fixed phases.•     Measure several points on each panel and compare neighbouring panels.

Use it when a gap is hard to reach with the front of the host. The flexible sensor works at 40 kHz on a bendable neck, so you can put its tip right at a panel gap.The host recognises it and switches to ultrasonic mode automatically. Readings are in dBµV and are judged with the same table as the built-in sensor: below 6 dB no discharge, 6–15 dB slight, above 15 dB serious. Measure the background in the air first, then hold the sensor still at the gap for 2–3 seconds before saving.Picture filepd-flexible-ultrasonic-sensor-switchgear.pngAlt textPenta PD flexible ultrasonic sensor on a bendable gooseneck for switchgear partial discharge testingCaptionThe flexible ultrasonic sensor.

Yes. Turn on Alarm Sound in the settings menu (the manual calls it the telegraph warning code). With it on, the tester beeps when you hold it near equipment that is discharging. The stronger the discharge, the faster and more urgent the beeping.It lets you sweep a switchroom quickly without watching the screen at every panel. When it beeps, stop and take a saved measurement at that point.

Use the external contact ultrasonic sensor. A discharge inside the transformer produces ultrasound that travels through the surrounding media to the tank wall, where the sensor converts it into an electrical signal.1.     Measure the ultrasonic background in the air first and remove any interference.2.     Place the sensor on the transformer housing. The contact face must be in good contact; apply a coupling agent where needed to reduce acoustic resistance.3.     Hold it still for 2–3 seconds, then save.4.     Do not slide the sensor around while measuring; that adds noise.5.     Test at several points on all sides of the transformer.Judge results with the same table as switchgear ultrasound: below 6 dB no discharge, 6–15 dB slight, above 15 dB serious.The contact sensor is very sensitive. Do not knock or drop it; impact can damage it permanently.Picture filetransformer-partial-discharge-contact-ultrasonic-test.jpgAlt textContact ultrasonic sensor placed on a transformer housing for partial discharge testingCaptionContact ultrasonic sensor on the transformer housing.

Use the UHF sensor at the insulating basin or observation window of each gas compartment, and the contact ultrasonic sensor on the metal tank.To judge a UHF result:1.     Check whether the signal has a typical discharge pattern, or differs clearly from the background and other test points.2.     If it does, rule out external interference: place the sensor on the insulating basin and compare with the signal measured in the air. If they are the same and the signal is small, it is most likely external interference. If they differ, or the basin signal is larger, investigate further.3.     Measure the neighbouring compartments and locate the discharge by amplitude (see the next question).4.     If needed, fix the sensor to the basin and record for at least 15 minutes, then analyse the PRPD and PRPS patterns to identify the discharge type.The instrument's built-in discharge analysis gives a reference diagnosis from the pattern. Where conditions permit, also use an ultrasonic PD instrument for accurate positioning.Picture filegis-partial-discharge-uhf-test-at-insulating-basin.jpgAlt textEngineer testing GIS for partial discharge with the Penta PD and a UHF sensor at the insulating basinCaptionUHF test at a GIS insulating basin.

Use signal attenuation. The signal weakens as it travels away from the source, so the measuring point with the highest amplitude is nearest to the discharge.•     UHF: measure at the insulating basins of adjacent compartments and compare amplitudes.•     Contact ultrasonic: place the sensor at several points along the tank and compare; the discharge position is judged from the detection amplitude.

1.     Clamp the HFCT directly around the cable's earthing lead or the earthed outer sheath.2.     Hold for 2–3 seconds. When the reading is stable, press Save.To judge the result:•     Check whether the signal shows a typical discharge pattern or differs clearly from the background and other test points.•     Horizontal comparison: similar cables in the same substation, in similar conditions, should give similar signals. One that stands out deserves attention.•     Vertical comparison: test the same cable regularly. A clear rise, or the appearance of a typical discharge pattern, marks an abnormal point.A signal with discharge characteristics but small amplitude is treated as an abnormal signal; with obvious characteristics and large amplitude, as a defect.Picture filecable-partial-discharge-hfct-test-on-earth-lead.jpgAlt textHFCT clamped on a cable earthing lead with the Penta PD reading the partial discharge signalCaptionHFCT on a cable termination's earthing lead.

Use the ultrasonic wave concentrator. It is a parabolic dish that collects the ultrasound a discharge on an insulator or fitting sends through the air, so you can test from the ground.1.     Connect the sensor to the host. Check that the screen shows the wave concentrator; if it does not, touch the sensor icon to select it.2.     Measure the background in the air first. If it is too high, find and remove the interference.3.     Point the concentrator at the insulator or fitting and hold it still for 2–3 seconds.4.     Record and save the reading.The concentrator works from 40 to 200 kHz.Picture fileoverhead-line-insulator-partial-discharge-wave-concentrator.jpgAlt textEngineer aiming the ultrasonic wave concentrator at an overhead line tower to detect insulator partial dischargeCaptionWave concentrator aimed at an overhead line from the ground.

From top to bottom:•     Sensor type and parameters: which sensor is active, its model and frequency band. With the built-in sensors, touch this area to switch between ultrasonic and TEV.•     Time-domain signal: the live waveform.•     PRPD map: discharge amplitude against phase.•     Progress bar: runs while a measurement is being saved.•     Measured value: the peak value. Green is below the yellow warning threshold, yellow is between the yellow and red thresholds, red is above the red threshold.•     Number of pulses per cycle and detection frequency.•     Discharge result: the real-time diagnosis.The four menu keys along the bottom are Settings (yellow), Save (red), Historical data (purple) and USB connection (orange).Picture filepenta-pd-test-screen-explained.pngAlt textPenta PD test interface with sensor parameters, time-domain signal, PRPD map, measured value and menu buttons labelledCaptionThe test screen, with each area labelled.

When you press Save, the tester collects the set number of power cycles, builds the PRPD and PRPS patterns and compares them with its built-in discharge reference. The save screen then shows:•     the PRPD and PRPS patterns•     peak value, signal voltage and pulses per cycle•     sensor type and synchronisation method•     the diagnosis, for example "It may be a high level of suspended potential"The report generated on the PC breaks the diagnosis down by type with a percentage for each: internal discharge, surface discharge, suspended (floating) potential, corona discharge and noise.Treat the diagnosis as a guide. Confirm it with the patterns, a second method where possible, and the equipment's history before deciding on action.Picture filepenta-pd-save-screen-with-discharge-diagnosis.pngAlt textPenta PD save screen showing PRPD and PRPS patterns with the diagnosis high level of suspended potentialCaptionSave screen with an automatic diagnosis of suspended potential discharge.

Free metal particle discharge is discharge between loose metal particles, or between particles and metal parts.Its pattern:•     amplitude spread over a wide range•     unstable time between discharges•     no clear difference between the positive and negative half-cycles•     signals across the whole power-frequency cycle, not clustered at fixed phasesPicture fileprps-pattern-free-metal-particle-discharge.pngAlt textPRPD and PRPS pattern of free metal particle partial discharge spread across the whole power cycleCaptionFree metal particle discharge.

Suspended potential discharge comes from a metal part that has come loose and is no longer firmly connected to either the high-voltage conductor or earth, so it floats at an intermediate voltage.Its pattern:•     stable pulse amplitude•     almost equal time between successive discharges•     when the floating part is asymmetric, a visible difference between the positive and negative half-cycle signalsPicture fileprps-pattern-suspended-potential-discharge.pngAlt textPRPD and PRPS pattern of suspended potential partial discharge with stable pulse amplitudeCaptionSuspended potential discharge.

This discharge happens inside solid insulation, at a crack, air gap or other defect.Its pattern:•     relatively few discharges•     poor repeatability from cycle to cycle•     scattered amplitude•     a stable discharge phase•     no obvious difference between the positive and negative half-cyclesPicture fileprps-pattern-insulator-internal-air-gap-discharge.pngAlt textPRPD and PRPS pattern of partial discharge in an internal air gap of an insulatorCaptionInsulator internal air gap discharge.

Metal tip discharge is SF6 corona caused by a concentrated electric field at a burr or sharp point on a part at high or low potential.Its pattern:•     many discharges•     small spread in amplitude•     even time between discharges•     at first, it appears only in the negative half-cycle of the power-frequency voltagePicture fileprps-pattern-metal-tip-corona-discharge.pngAlt textPRPD and PRPS pattern of metal tip corona partial discharge in the negative half-cycleCaptionMetal tip discharge, starting in the negative half-cycle.

Look at the time-domain waveform and the PRPD map together:•     General environmental noise has a similar amplitude across the whole phase range.•     A discharge signal is a small number of pulses whose amplitude stands out clearly, at repeatable positions in the cycle.On the PRPD map, a real discharge builds up clusters at fixed phase angles as the cycles accumulate. Noise spreads evenly or drifts. When in doubt, compare with the background and with neighbouring equipment, and repeat the measurement.Picture filetime-domain-waveform-and-prpd-map.pngAlt textTime-domain partial discharge waveform and PRPD map with pulses clustered at fixed phasesCaptionTime-domain waveform (left) and PRPD map (right) of a real discharge.

The manual describes two comparisons:•     Horizontal comparison: similar equipment in the same substation, in a similar environment, should give similar signals. One unit that stands out from its neighbours deserves attention.•     Vertical comparison: measure the same point on the same equipment repeatedly over a long period. A significant rise, or a typical discharge pattern appearing, marks that test point as abnormal.To make trending work, save every measurement with a file name that identifies the equipment and point (the manual recommends the actual panel number), measure at the same points each time, and keep the background reading with the result.

The power switch is a touch key. Touch the power mark until you hear a "drip" sound, then release; the tester starts.•     Status indicator S (green): flashes during normal measurement. It goes off when the tester is connected to the PC software.•     Charge indicator C: lights while the battery is charging and goes off when it is full.Use the same touch key to switch off.Picture filepenta-pd-power-switch-and-status-indicators.pngAlt textPenta PD touch power switch with charge indicator C and status indicator SCaptionTouch power switch with the charge (C) and status (S) indicators.

Charge through the USB port, either from a computer's USB port or from an ordinary 5 V DC supply rated 500–1,000 mA. The supplied charger accepts 90–264 V AC.•     Charge before using the tester for the first time.•     Switch the tester off while charging, to avoid interference or leakage.•     Do not exceed 5.5 V DC. The tester has over-voltage protection, but long-term over-voltage charging can damage it.•     The battery is full when the C indicator goes off and the screen shows a full battery. On the supplied charger's display, charging is complete when the current falls below 0.1 A.The internal 3.7 V, 5,000 mAh lithium battery gives about 6 hours of use. Lower screen brightness and a short automatic shutdown time extend it.

Touch the sensor status area at the top left of the screen. The built-in ultrasonic sensor (40 kHz) is selected after power-on; one touch switches to the built-in TEV sensor (3–100 MHz), and the frequency and model shown change to match.This switch only works for the built-in sensors. When an external sensor is plugged in, the tester recognises it and selects it automatically.Picture filepenta-pd-switch-ultrasonic-to-tev-sensor.pngAlt textPenta PD sensor status area switching from ultrasonic 40 kHz to TEV 3 to 100 MHzCaptionTouching the sensor area switches from ultrasonic (40 kHz) to TEV (3–100 MHz).

The sensor port uses a precision connector, so handle it with care:•     Connect the sensor before you start testing. Never plug in or unplug a sensor while a measurement is running.•     Line up the mark on the plug with the mark on the socket and push straight in until it clicks.•     Do not twist the connector once it is in.•     To remove it, hold the metal shell of the connector and pull straight out. Never pull on the cable.

Touch the yellow key on the test screen to open settings:•     Automatic shutdown: switches off after a set time to save battery.•     Screen brightness: raise it in strong sunlight, lower it indoors for longer battery life.•     Date and time.•     Network: Wi-Fi data transfer, on models with the optional Wi-Fi function.•     Threshold setting: the yellow and red warning levels.•     Number of cycles: how many power cycles are collected for the PRPS pattern.•     Wireless sync.•     Alarm sound: the audible discharge alarm.Press OK to return to the test screen.Picture filepenta-pd-settings-menu.pngAlt textPenta PD settings menu with automatic shutdown, screen brightness, date, time, network, threshold, cycles, wireless sync and alarm soundCaptionThe settings menu.

The default is 10 cycles, and 10 to 30 is the usual range. There is no single standard value.Each cycle is 20 ms on a 50 Hz system, so 10 cycles take 0.2 seconds of signal. More cycles give a fuller pattern but lengthen every saved measurement. The manual recommends staying below 30.

The yellow and red warning thresholds are set at the factory, and you can change them. Open Settings, choose Threshold Setting and use the + and − keys next to each item.The thresholds decide the colour of the measured value on the test screen: green below the yellow threshold, yellow between the two, red above the red threshold.

1.     With the sensor in position, press the red Save key. The progress bar starts and the test count increases.2.     Keep the sensor close to the equipment until the bar finishes, or the data will not be valid.3.     The save screen shows the PRPD and PRPS patterns, peak value, sensor type, voltage, pulse count and diagnosis.4.     Press OK and type a file name on the on-screen keyboard.Use the actual panel or equipment number in the file name. It makes later trending and report writing much easier.Picture filepenta-pd-save-screen-with-discharge-diagnosis.pngAlt textPenta PD save screen with PRPD and PRPS patterns, peak value, voltage and pulses per cycleCaptionThe save screen appears when the progress bar completes.

Files are saved in the root directory of the SD card (16–64 GB fitted as standard).•     To view: touch the purple Historical data key on the test screen. A file list opens; double-tap a file to show its data and patterns.•     To delete: select the file and touch Del.•     New Folder lets you group files, for example by substation.To move files to a computer, connect by USB and use the PC software (section G).Picture filepenta-pd-historical-data-file-list.pngAlt textPenta PD historical data view listing saved partial discharge test filesCaptionHistorical data view.

Yes. Plug earphones into the 3.5 mm stereo jack on the host; they must be 8 Ω or more. In ultrasonic mode the tester filters the ultrasonic signal digitally and converts it into sound you can hear.This lets you hear the discharge sound inside the cabinet while you hold the sensor at a gap.

Only on units with the optional Wi-Fi function. On those, turn on Network in the settings menu; data can be transferred once the tester is connected to the computer.Every unit can transfer data by USB cable with the PC software.

The PC software is the partial discharge data management software, version 1.32.1.     Double-click the installer.2.     Choose whether to create a desktop shortcut, then click Next.3.     Click Install.4.     If a "Preparing to install" screen appears, click Next.5.     Click Finish.The first time you run it, it asks to install the CH340 USB driver (next question).

The software needs the CH340 USB driver to communicate with the tester. When the software starts for the first time it detects that the driver is missing and offers to install it. Click Yes, then Install, and wait for the "Driver installation successful" message.Without the driver the software cannot connect to the tester.

1.     Connect the tester to the computer with the USB cable.2.     Click Device Connection in the toolbar and wait for the connection prompt; click OK.3.     Files are organised as Workstation, then Detection Device, then Data File. Right-click the blank file area, choose New Workstation and enter the substation name.4.     Right-click the substation and choose Add Detection Device.5.     Right-click the device and click Import Device File. The tester's file system opens.6.     Double-click the files you want; they are copied into that device's folder. Right-click and use Refresh Directory to update the list.7.     When finished, click Disconnect Device.Picture filepd-data-management-software-main-window.pngAlt textPartial discharge data management software main window with device file management, PRPD and PRPS areas and discharge type resultsCaptionThe PC software: file management on the left, patterns and results on the right.

1.     Open the imported data file.2.     Click Generate Test Report in the toolbar.3.     Fill in the editable fields: station, voltage level, equipment, test conditions, conclusion.4.     Click Print Report for a print preview, then choose your printer.Or click Generate Excel, enter a file name and save the report as an Excel file to edit or print later.The report includes the PRPD and PRPS patterns, detection cycles, pulse count, synchronisation method, sensor type, discharge intensity and the percentage breakdown by discharge type.Picture filepartial-discharge-test-report-from-pc-software.pngAlt textPartial discharge test report generated by the PC software with PRPD and PRPS patterns and discharge type percentagesCaptionGenerated test report, with patterns and diagnosis.

The manual provides report templates for switchgear, transformers, cables and GIS. The fields vary slightly between templates, but each has three blocks:1.     Essential information: substation, client, test unit, test nature, test date, test personnel, report date, prepared by, reviewed by, weather, ambient temperature and relative humidity. Most templates also record run number, test location and approver.2.     Equipment nameplate: manufacturer, date of production, factory number, equipment model and rated voltage.3.     Test data: one row per measuring point, with the location or test value, the pattern (atlas) file and whether discharge was found. Depending on the template, a detected peak or the load current is also recorded.Each ends with a feature analysis, a conclusion and remarks. Following the same template every time makes results comparable year to year.