The relay has certain advanced features such as Cold load pickup, MlPConS and auto re-close relaying that improve the sensitivity, stability and availability of the system.

 

JVS Electronics Pvt Ltd - an exporter, manufacturer and supplier of audio indicating instruments, visual indicating instruments, electrical indicating instruments, etc – has developed numerical communicable over current relay with auto recloser.

  

Application

 

The relay provides time graded phase and earth fault (2 stage) protection, (high impedance) restricted earth fault/sensitive earth fault protection in addition to various other advanced protection features. MODBUS communication protocol over RS-485 facilitates interfacing of the relay with SCADA systems and RS-232 communication port provided at the front of the relay allows engineers to program the relay with ease. Certain advanced features such as “Cold load pickup”, MlPConS and “Auto re-close relaying” improve the sensitivity, stability and availability of the system.

 

Protection & control

 

Phase over-current, earth fault, sensitive earth fault / restricted earth fault protection features can be enabled or disabled independently. However, inhibition of all protection functions is not allowed.

 

Over current protection

 

The relay measures the line current from each of the line CTs and if the current exceeds the set threshold, then the relay extends a trip signal after an operating time. The relay’s “operating time” is determined by seIecting “definite time” or one of the six “inverse time” characteristics. This principle of relaying is equally applicable to both line and earth fault protection elements (5IN/ 5IG).

 

MIPConS: Management of Imbalance Phasor Control through Supervision

 

Under the existing practice of operating the distribution network in 2-phase mode (popularly known as single-phasing) for certain strategic purposes, conventional earth fault relays in substations would pick-up and trip the circuit breaker. This operation is considered by the engineers as an undesirable outcome of a planned current un-balance in the system. “MlPConS”, when enabled, automatically detects the single phasing and restoration operations of 3-phase system. Consequently, the feature prevents “earth fault element” from extending the trip command under single-phasing conditions. MIPConS uses certain complex pattern recognition techniques and adaptive relaying principles to provide sensitivity and stability for the earth-fault relay and therefore, neither does it require any potential transformers nor any extra settings for its operation. This considerably reduces cost of potential transformers, wiring and eliminates the need of programming another relay such as NVDR/NDR.

 

Cold load pick-up

 

This feature can be useful in providing better selectivity in the operation of over current relays by preventing them from operating during inrush phenomenon.

 

Auto re-close facility

 

A multi-shot auto re-closer facilitates automation of breaker operation. Auto re-closer can be programmed to provide a maximum of five shots. “Dead time” starts when a trip signal is provided due to the occurrence of a fault involving L-L or L-G or L-L-G or L-L-L or L-L-L-G. After an elapse of a time interval equal to “dead time”, closing command will be extended. The “reclaim time” timer starts at the instant when the “dead time” timer expires. If, after extending the “breaker close” signal, an over current fault was detected before the “reclaim time” timer reached its terminal count, then the relay understands that the fault in the system is still persisting and the over current relay will issue a trip signal. The relay tries to close the breaker for a maximum of the programmed number of shots before it chooses to lockout. The relay can be configured for independent trip sequence such as IDMT or Definite time.

 

Trip test facility

 

The trip test will facilitate the testing of relay operation without applying the input current. The trip test is useful to test the panel wiring and operation of the breaker without any current. The trip contact will operate instantaneously.

 

The phase and earth fault alarm contact will not operate during the trip test.

 

Records

 

The relay can store upto 300 various records at any given point of time. These records can assist in analyzing power system events and system behavior.

 

Fault records: A list of 200 fault records are provided in the relay. A fault record is captured at the occurrence of a fault with a time tag. Each fault record contains the magnitude of the fault, line parameters and the settings of the relay.

 

Event records: The relay can store up to 100 event records. Event records capture various types of events that occur in a relay along with the time of day information.

 

Disturbance records: Disturbance records are captured at the tick of a trigger. In most cases, the trigger happens to be a fault event. The record comprises of post-event data and pre-event data. The record itself comprises of sampled valued data and other events complying to IEEE COMTRADE format.

 

Communications

 

RS - 232 communication port provided at the front of the relay allows engineers to program the relay with ease. MODBUS communication protocol over RS-485 facilitates interfacing the relay with SCADA systems. RS-485 network allows multiple relays/IEDs to be interfaced with a common station computer over the same physical network.

 

JVS Electronics Pvt Ltd is an exporter, manufacturer and supplier of audio indicating instruments, visual indicating instruments, electrical indicating instruments, etc.

 

For details, contact JVS Electronics Pvt Ltd, Ramanagara (Karnataka), on Tel: 080 2720 4211/12/13, or Email: bangalore@jvselectronics.in

 

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