Relay Test Kits
Videos - Relay Test Kits
Theory - Relay Testing
Relay Testing Kit – Theory
Protective relay is a device which maintains the power system equipments and gives an output under an abnormal condition to ensure protection of the system. The basic objective of the protective relay is to isolate the faulty section in a power system as quickly as possible so that rest of the system functions normally. It is necessary to ascertain security, reliability, quality, sensitivity and speed of relays.
Various tests are recommended in National and International Standards to check the withstand capacity of a relay during fault conditions. During testing, protective relay is made to undergo simulated field conditions to check its performance. The relevant National / International standards recommend many tests to ascertain the relays effectiveness to perform its intended function.
A Relay receives the input signals from CT’s/ PT’s and its program calculates the fault conditions as per application. It issues a trip command to the Circuit Breaker on sensing a faulty condition. On the basis of application, Relay may be classified into below types:
Relay Testing Kit injects fault in form of I & V on respective CT & PT points of Relay under test . The Timer of Relay Testing Kit starts by initiating fault injection.
Relay senses the fault & issues the trip command, its trip timing must depend on the time characteristics of relay settings.
Relay Testing Kit receives the trip command from Relay & Stops the timer.
The measured tripping characteristics are compared with respect to expected tripping as per settings by Engineer.
The basic connection of protection relay has been shown in the picture. The secondary of current transformer is connected to the current coil of relay. The secondary of voltage transformer is connected to the voltage coil of the relay. Whenever any fault occurs in the feeder circuit, proportionate secondary current of the CT will flow through the current coil of the relay due to which mmf of that coil increases. This increased mmf is sufficient to mechanically close the normally open contact of the relay. This relay contact actually closes and completes the DC trip coil circuit and hence the trip coil is energized. The mmf of the trip coil initiates the mechanical movement of the tripping mechanism of the circuit breaker and ultimately the circuit breaker is tripped to isolate the fault.
Types of Relay as per various requirements:
Over Current Relay
Frequency Actuated Relay
Directional Over Current Relay
Restricted Earth Fault Relay
Over Fluxing Relay
Distance Schemes Relay
Bus bar Protection Relay
Reverse Power Relay
Loss of excitation Relay
Negative Ph. Sequence Relay
Energy Meters Relay
Fault Playback Relay
Frequently Asked Question
Relay Test Kit
What is a relay test kit ?
A relay test kit is an equipment which is used for testing different type of relays. Relay test kit is a combination of programmable current and voltage sources and a timer . During relay testing Relay test kit injects fault in the relay (in form of CT & PT ) and measures the tripping time or reaction time of the relay. If the behaviour of the relay is as per its settings then the relay pass the test else relay fails the test .
Why automatic relay test kits are preferred over traditional ( variac based ) relay test kits ?
Automatic relay test kits have various advantages over traditional kids
1. Signal Stability : The output the current and voltage output of automatic relay test kit is not proportional to its input power supply it means the current and voltage output of relay test kit are getting supply from analogue to digital and then digital to analogue conversion backed with a feedback loop hence the output signals off relay test kit are not dependent on its input power supply . Automatic Relay Test Kit output are stable even if there's there is some minor instability in the input power supply
What is a numerical relay test kit?
Numerical relay test kit is an another name for automatic or microprocessor based relay test kits . Numerical relays generally high accuracy which can be tested with highly accurate automatic relay test kits
What is a universal relay test kit ?
Universal Relay Test Kit is another name for automatic relay test kits as user can vary phase , frequency and magnitude of the current and voltage sources independently and generate any type of fault .
What is 6 Phase relay Test Kit , when there is only 3 phase CT or PT in power system ?
Many customers are confused with the notation of 6 phase relay test kit . The high end relay test kits have six current sources whose phase frequency and magnitude can be varied independently . These 6 current sources are very useful in testing a differential relays.
What is need of advance software with Automatic Relay Test Kits ?
As we know that each fault is generated due to variation of Phase, frequency or magnitude in CT or PT signal , Few fault simulations are not very simple ( like testing Quadrilateral characteristics of Distance Relays ) . Advance software are very useful in simulating complex faults . Kingsine User gets all in one advance software in their standard purchase .
Why high current and voltage amplifiers are desirable in relay test kits
It is truly said that Current and Voltage sources are the soul of relay test kit .
High current and voltage signal is useful in below ways
- For testing 5A Over Current Relays at 10 Times , we have to inject 3X50A , which is possible with high current relay Test Kits
- With higher current we can test a differential relay at higher point of BIAS Curve .
- With higher Currents we can simulate higher faults in Transient Fault Playback .
Kingsine Test Kits have the highest Current Rating sources of 0 to 35A each ( @450VA ) and 0 to 300V each ( 124 VA )
Why high power amplifiers are desirable in relay test kits ?
Relay Test Kits with high power amplifiers are preferred as high power is required for testing the electromechanical relays . Also if a relay test kit is having higher power rating then its duty cycle for lower power rating is high hence more rugged design . Kingsine is having most powerful current sources of 480VA ( @35A ) each and most powerful voltage sources of 124VA ( @310V ) each
What is more important , Advance software or powerful hardware in selecting an automatic relay test kit ?
A powerful hardware is most important for long time robustness of a relay test kit, Few application needs high powered sources also .
An advance software is a tool which helps user to test even most complex relays in the easiest way .
Hence in today’s scenario relay test kit shall be a combination of high rated sources and advance software . K3063i is a good combination for both
Why Kingsine relay test kits have highest power rating in market ?
In Kingsine each current Source is of 480VA @35A and Voltage Source is 124VA@310V , hence highest in the market .
Why Kingsine K3063i is the best combination of power and accuracy ?
K3063i is having high powered voltage and current source ( current Source is of 480VA @35A and Voltage Source is 124VA@310V) while it is having current range of 3 A, which leads to very high accuracy in lower currents .
Whom to contact for any KPM’s test equipment support ?
Feel free to contact our Technical Consultant on Consultant@kpmtek.com for any queries .
Where is the service centre of Kingsine relay test kits located in INDIA ?
We have an advance service center in Gurgaon, Haryana with 100% spare availability .
What is df/dt relay , Can I test it using Kingsine Relay Test Kits ?
Rate of Change of Frequency (ROCOF or df/dt) relay is used for fast load shedding, to speed up operation time in over- and under-frequency situations and to detect loss of grid.
ROCOF or df/dt relays are particularly effective in arresting the frequency collapse of a grid in the event of sudden loss of major generation. This is because by measuring the frequency decay rate, the corrective action can be initiated much ahead of the time when frequency of the synchronous interconnection would have actually dipped to a point at which generator under-frequency relays or unit auxiliaries would trip / operate leading to a complete system shutdown. The df/dt is used for load shedding in situations where sudden loss of generating capacity on a system will be accompanied by a decrease in system frequency. In such a situation of load Generation mismatch, the system frequency tends to fall. The df/dt relay can control the circuit breakers and allow feeders to be disconnected from the network, one by one.
In Kingsine Software there is a specialised module for testing of df/dt
What is distance relay , Which relay test kits can test these relays ?
A Distance relay / impedance relay is a voltage restrained overcurrent relay. The relay measures impedance up to the point of fault and gives tripping command if this impedance is less than the relay setting Z. Relay setting Z is known as replica impedance and it is proportional to the set impedance i.e. impedance up to the reach of the relay. The relay monitors continuously the line current I through CT and the bus voltage V through PT and operates when the V/I ratio falls below the set value.
In Kingsine both K68i & K3063i have specialised modules for testing of distance relays .
Why high power relay test kit is required for testing a electromechanical relays
Electromechanical relays have high impedance coils , during testing relay test kit has to inject current via coils of high impedance hence high burden is required . Kingsine kits have highest burden hence ideal for testing all type of relays .
What is advance Transient playback function of automatic relay test kit ?
Now a days all advance relays comes with a fault recorder function . Whenever fault strikes this fault file gets saved in relay in form of .cfg / comtrade file . Relay test kit have the feature to import this file in its software and replay the file using its current and voltage sources . This is called as Transient playback feature.
What are the precaution with connections to kept in mind while operating relay test kit ?
Few of the site precautions are -:
- All the CT and PT terminals which are to be connected to relay test kit shall not be live .
- Earthing shall always be connected to the kit .
- During testing high current surge equipment such as welding sets shall be avoided in the same power supply circuit of relay test kit .
- Always work as per relevant local or international standard of testing .
What type of protection features are existing there in Kingsine Automatic Relay Test Kits ?
Kingsine Relay Test Kits have below protections
- Short Circuit protection got Voltage Amplifiers
- Open circuit Protection for current amplifiers
- Over Heat Protection .
- Health Earth Indication etc.
I want to test Differential Relays which type of relay test kit is more suitable for me ?
For testing differential relay on 3 phase basis we need 6 Current Source relay test kit i.e. K3063i , We can test a differential relay on phase to phase basis also using a 3 current source relay test kit , K68i