DEIF MVR-200 Medium Voltage Relay: Installation and Wiring Engineering Guide

5. Output relay wiring

Attention should be paid to the total current carrying capacity limit of the module. For example, the DO5 tab has a maximum total current of 3A at 220V AC and 0.2A at 220V DC. Exceeding the limit may cause module overheating or damage.

Typical application wiring example

The MVR-200 series covers various power protection scenarios, and the manual provides detailed wiring diagrams. Here are a few typical configurations:

1. Feedline protection (F205/F210/F215/F255)

Measurement signal: three-phase current (CT)+residual current (optional)+three-phase voltage (VT, optional)+zero sequence voltage (optional).

I/O configuration: Digital input is used for circuit breaker position feedback (5a/56a); Digital output is used for tripping, closing, and control.

ARON wiring: For situations with only two-phase CT, ARON wiring method (V connection) is supported, and the third phase current can be calculated. However, it should be noted that this method cannot detect the second phase to ground fault, and an additional cable core CT should be provided for grounding protection.

2. Motor protection (M210/M215/M255/M257)

M210: Supports overload, locked rotor, start monitoring, etc., requiring only three-phase CT.

M257 (motor differential): Install one set of CT on each side (neutral point side and outgoing line side) of the protected motor, and both sets of CT are connected to the CT module of M257. When a turn to turn or phase to phase short circuit occurs internally, the differential current increases, triggering a rapid trip.

3. Generator protection (G215/G257)

G215: Suitable for small and medium-sized generator sets, providing protection against overcurrent, grounding, over/under frequency, reverse power, etc.

G257 (Generator Differential): Supports individual differential of the generator or combined differential of the generator and transformer. Two sets of CTs are installed on the neutral point side and the outgoing line side (or both sides of the transformer) of the generator to achieve rapid internal fault protection.

4. Transformer protection (T215/T216/T256/T257)

T215 (Voltage Regulation): Suitable for on load tap changer (OLTC) control of on load tap changers. In addition to measuring current and voltage, mA input can be connected to tap changer position feedback, and digital output controls the "boost/buck" command.

T216/T256/T257 (Transformer Differential): Used for differential protection of double winding transformers, supporting high voltage and low voltage CT connections, and equipped with high voltage side limiting stator grounding protection (REF).

Trip Circuit Monitoring (TCS, ANSI 95): Key Engineering Details

The integrity of the trip circuit is a prerequisite for protecting correct operation. The MVR-200 provides a mature solution for implementing TCS using a single digital input, and the manual provides a very detailed explanation of this:

TCS under Non tapped Output: When the trip relay is non tapped, the TCS circuit continuously monitors the integrity of the trip coil circuit through digital input (normally closed mode) in the closed state of the circuit breaker. Once the circuit is disconnected or the auxiliary power supply is lost, the DI will flip and trigger an alarm. Key setting: The activation delay of this DI should be set to 1.0 second to avoid the brief circuit interruption caused by the normal opening operation of the circuit breaker.

TCS under Latched output: If a hold type output is used, the DI will be short circuited by the tripping contact after the circuit breaker trips, and monitoring cannot continue. At this point, the TCS alarm must be blocked through internal logic when the circuit breaker is opened, and monitoring must be restored after the circuit breaker is closed again, otherwise false alarms may occur.