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

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

Introduction: A New Generation Universal Platform for Medium Voltage Protection

The protection reliability of medium voltage (MV) switchgear and rotating equipment is directly related to personnel safety and production continuity in industrial distribution, ship power systems, and renewable energy power stations. Traditional discrete protection relays have a single function and are difficult to adapt to increasingly complex system requirements; Modern intelligent electronic devices (IEDs) not only need to provide complete protection functions, but also require flexible hardware expansion capabilities, fast response speed, and adaptability to harsh environments.

The DEIF MVR-200 series medium voltage relay is a universal protection platform that emerged in this context. It covers various application scenarios such as feeders, motors, generators, transformers, and voltage protection. With a modular hardware architecture, rich communication interfaces, and powerful expansion capabilities, it provides highly flexible protection solutions for system integrators and cabinet manufacturers. This article will systematically analyze the hardware modules, installation specifications, wiring points, and typical applications of MVR-200 based on the official installation manual, providing comprehensive technical references for engineers engaged in the design and implementation of medium voltage protection systems.

Product Series and Model System: Accurately Matching Application Requirements

The MVR-200 series adopts a clear naming convention for product models, allowing engineers to quickly select the correct model based on the application scenario.

Typical functions of model prefix application scenarios

MVR-F2xx feeder protection (Feeder) overcurrent, ground fault CBFP、 Automatic Recloser

MVR-M2xx motor protection (Motor) overload, locked rotor, differential, start monitoring, thermal protection

MVR-G2xx Generator Protection: Differential, Reverse Power, Over/Under Frequency, Stator Grounding

MVR-T2xx Transformer Protection: Differential, Overcurrent, Grounding, Temperature Monitoring

MVR-V2xx Voltage Protection: Over/Under Voltage, Frequency, Vector Jumping ROCOF

The main hardware differences among various models are reflected in the configuration of the measurement module:

F201/M210/V211 and other 21x series: 1/4 19 inch rack width, suitable for compact switchgear.

F255/G257/T257 and other 25x series: 1/2 19 inch rack width, supporting more analog and I/O expansion.

Deep Analysis of Hardware Modules: Building an Scalable Protection Platform

The MVR-200 adopts a modular slot design, and users can choose different functional modules according to their application needs. All modules are installed in standard chassis and support 19 inch rack mounting or panel opening mounting.

1. CPU, I/O, and power module (core module)

This is the basic module of every MVR-200 device, integrating the processor, communication interface, basic I/O, and power supply.

Processor and Memory: Based on high-performance microprocessors, all binary inputs are sampled with a 5ms scan cycle to ensure fast response to protection signals. The control of the output relay is also completed within a 5ms cycle, and the theoretical delay from input detection to output action is about 0-15ms (excluding the mechanical action time of the relay).

Communication interface:

COM A (RJ-45): Used to connect MVR debugging software (Utility Software) and station control layer protocols such as IEC 61850, Modbus TCP, DNP3 TCP, etc.

COM B (RS-485): Used for serial SCADA communication such as Modbus RTU, DNP3, IEC 103, etc., supporting multi-point bus topology.

Digital input:

MVR-21x provides 2 or 3 digital inputs, while MVR-25x provides 3. The rated threshold voltage can be selected from 24V, 110V, or 220V DC to adapt to different levels of switch signals.

Each digital input supports software configurable features such as activation delay, drop off time, polarity selection (NO/NC), and AC mode (used for anti jitter processing of AC input signals).

Digital output:

5 output relays, including 4 normally open (NO) contacts and 1 conversion (CO) contact. Rated voltage 250V AC/DC.

System Fault Relay: a switching contact that closes (16-18) when the equipment is powered on normally and there is no system fault, and closes (16-17) when the equipment loses power or an internal fault is detected, used to achieve "fault safety" monitoring.

Power Supply:

Optional H-type (100~125V DC) or L-type (24/48V DC) to meet the requirements of different DC power supply systems.

The power supply has a power-off holding time of>150ms, a maximum power consumption of 15W, and a startup time of<5ms.

2. Current measurement module (CT module)

This module provides 5-channel current measurement inputs, which are the basis for most feeder, motor, and generator protections.

Channel allocation: 3 phase current inputs (L1/L2/L3)+1 rough residual current (I01)+1 fine residual current (I02).

Rated value and accuracy: The rated secondary current is 5A (adjustable by software within the range of 1-10A), with an accuracy of ± 0.2% within the range of 0.05 × In~4 × In.

Range and Frequency: The phase current measurement range is 0.25A RMS, and the frequency measurement range is 6Hz~1800Hz, suitable for power systems of various frequencies (including intermediate frequency and variable frequency applications).

AD conversion: 18 bit ∑ - Δ ADC, sampling 64 points per power frequency cycle to ensure high-precision measurement.

3. Voltage measurement module (VT module)

This module provides 4-channel voltage measurement inputs and supports flexible configuration.

Input characteristics: Each channel has a range of 0~480V RMS (can be directly connected to low-voltage systems or VT secondary side), and a rated voltage range of 100~400V.

Accuracy: ± 0.2% (within the range of 0-240V), with angle measurement accuracy better than ± 0.5 °.

Configuration mode:

3LN+U4: Three phase four wire system (three-phase to ground voltage+zero sequence voltage).

3LL+U4: Three phase three wire system (three wire voltage+zero sequence voltage).

2LL+U3+U4: Two line voltage+calculated value of the third phase+synchronous check input.

Frequency and Sampling: Same as CT module, supports 6-1800Hz, 64 points/cycle sampling.

Troubleshooting tip: The manual provides a detailed troubleshooting table for voltage measurement. When the measurement value is abnormal, the VT ratio setting and measurement mode configuration should be checked first, and then the wiring polarity and phase sequence should be checked. The problem can be quickly located by viewing the "System Voltage Vector Diagram".

4. Arc protection module (option D)

Arc fault is one of the most serious electrical accidents in medium voltage switchgear, which can generate high temperature and high pressure gas within milliseconds, causing serious equipment damage. The arc protection module of MVR-200 is optional (Option D), supporting two types of sensors: optical arc detection and light+pressure composite detection.

Sensor channels: 4 sensor channels, each channel can connect up to 3 arc light sensors in series (daisy chain topology), and a single module can support up to 12 sensors.

Action logic: Supports the combination criterion of "arc light AND overcurrent", which means that the trip will only be triggered when arc light is detected and overcurrent/residual current exceeds the standard, effectively avoiding misoperation caused by external light source interference.

High speed output: The module is equipped with 2 high-speed outputs for quick tripping, ensuring fault removal within 5-10ms.

5. Expand I/O modules

Binary input module (DI8, option B): 8 additional digital inputs, input threshold can be set by software (16~200V), with AC mode anti jitter function.

Binary output module (DO5, option C): 5 additional output relays, including 2 conversion contacts and 3 normally open contacts.

MA Input/Output Module (Option I): 4 mA outputs+1 mA input, used to connect 4-20mA sensors or output analog control signals.

RS-232 communication module (options L/M/N/O): Provides serial fiber optic interface and RS-232 interface, supports IRIG-B time synchronization.

LC100 Ethernet module (option J): 2 100Mbps fiber optic Ethernet ports, supporting HSR/PRP redundancy protocol (IEC 62439-3), meeting the requirements of high reliability substation automation.

Installation and wiring specifications: ensure long-term reliable operation of the system

1. Mechanical installation

MVR-21x (1/4 rack width): Compact in size, 4 devices can be installed side by side in the same 19 inch rack. The size of the panel opening can be found in section 2.2.1 of the manual.

MVR-25x (1/2 rack width): 2 devices can be installed side by side in the same rack, providing more expansion space.

Ventilation requirements: The equipment should be installed on the flat surface of the "Type 1 enclosure" and ensure sufficient heat dissipation space.

2. Protective Grounding (PE)

Use a minimum 2.5mm ² grounding cable to reliably connect the grounding terminal on the back of the equipment to the grounding busbar of the switchgear.

The tightening torque of the grounding terminal is 0.5~0.6 N · m. After the device is powered on, the grounding connection must not be disconnected.

3. Auxiliary power supply wiring

For L-type (low-voltage DC) power supply: It is recommended to install a 4A slow melting fuse on each positive and negative power supply line, and to connect anti reverse diodes (withstand voltage ≥ 100V) in series in the backup power supply circuit.

Power redundancy requirements: For classification society applications, MVR must use reliable dual power supply (main+backup). When the main power supply fails, the backup power supply should be able to immediately take over to ensure uninterrupted protection functions.

Important warning: When MVR loses power, the equipment does not provide any protection function, and all relays will de energize. Therefore, the design of the switchgear must consider backup protection measures in the event of MVR power failure.

4. Voltage measurement wiring

It is recommended to install a 2A slow melting fuse for each voltage measurement circuit, and to be as close as possible to the secondary terminal of the voltage transformer (VT) to protect the measurement circuit and MVR input channel.

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.