DEIF MDR-2 multifunctional differential relay

DEIF MDR-2 multifunctional differential relay

Basic Information

The product model MDR-2 motor/generator specific multiphase differential protection relay belongs to the DEIF Multi line 2 series and is a complete design and commissioning manual for complete cabinet designers.

Suitable for cabinet design engineers, electrical debugging personnel, and ship/power station relay protection personnel; Includes full process instructions for safety specifications, hardware, wiring, protection curves, and parameters.

The core positioning of the three-phase phase separation differential protection device is used for internal short-circuit fault protection of synchronous generators and high-power motors. The fault alarm and tripping are achieved by collecting current from both sides of the CT and calculating the differential current.

Safety and General Pre Specification

1 Warning classification

Warning: High voltage live working and violations may cause personal injury or permanent damage to equipment. It is prohibited to directly touch the AC current sampling terminal;

Note: The factory parameters are only universal mean values and must be readjusted before the unit is put into operation. They cannot be used directly.

2 Legal and electrostatic requirements

Unauthorized disassembly will result in loss of warranty, and DEIF will not be held responsible for installation and operation accidents;

ESD electrostatic protection is required during the installation phase, and no protection is needed after wiring is completed;

Only certified high-voltage electrical personnel are allowed to carry out installation and commissioning operations.

3. Purpose of the manual

Complete coverage of product functions, hardware terminals, primary star/delta CT wiring, panel operation, differential curve tuning, and all parameter menus, it is the only complete reference document for design, wiring, and on-site tuning.

Basic technical specifications of the product

Power supply 12/24VDC wide voltage (8-36V), maximum power consumption 11W, short-term withstand 10ms 0V drop (reference 24V);

Applicable frequency: 30~70Hz, taking into account 50/60Hz power frequency;

CT secondary compatibility 1A/5A, with a maximum CT load of 0.3VA per phase;

Measurement accuracy: 0.1 In~In interval error of 1% In, when>In, the error is 1% measured current;

Electrical isolation: withstand voltage of 3250VAC/1min between AC current circuit and digital IO, meeting the standards of classification society;

Output contacts: relay 250VAC/8A, 24VDC/1A; Digital input 6~32VDC bidirectional optocoupler, impedance 2.4k Ω;

Response speed: Differential protection action<50ms;

Protection level: IP40 for the shell, IP20 for the terminals, and up to IP54 for the operation panel with added sealing gaskets;

Installation method: DIN rail installation/fixed with a base of 6 screws, the whole machine weighs about 1kg;

10 Environment: Operating at -25~70 ℃, Storage at -40~70 ℃, DIN 40040 HSE climate rating, Plastic UL94-V1 flame retardant;

11 Certification: CE, EMC IEC 61000 series, adapted to marine standards.

Core differential protection principle

1-phase independent differential detection

Three phase independent comparison winding CT current on both sides: L1 primary side I1 ↔  Similarly, for L1 secondary side I2 and L2/L3, the differential current Id is calculated separately for each phase. Any phase exceeding the standard can trigger an alarm/trip, accurately distinguishing between single-phase and inter phase internal short circuits.

Two segment characteristic curves (alarm curve Y1W/Y2W, trip curve Y1T/Y2T)

Horizontal axis Is=balanced current (percentage of load current to rated In), vertical axis Id=percentage of differential current, parameter range:

X1 (turning point): 50%~500% In;

Y1 (low constant value): 5%~45% In;

Y2 (high range constant value): 25%~95% In;

The alarm and trip share the X1 inflection point, and each has an independent delay adjustable from 0.01 to 2 seconds.

3 Additional Fixed Trip Logic

Two sets of fixed values, 100% In differential current fixed trip and 85% In fixed trip, are used as backup protection.

4 panel display function

Real time display: primary current I1, secondary current I2, balance current Is, and differential current Id (actual value+percentage) for each phase; Up to 150 timestamp event/alarm logs; Full parameter panel tuning.

5 panel buttons and LED indicator lights

button

INFO alarm list, LOG event record, JUMP menu direct access, SEL confirmation, up, down, left, right navigation, VIEW switching measurement screen, BACK return.

Front LED

Power supply, self-test normal, communication, short circuit I>>, overcurrent I>, differential alarm Id left light, differential trip Id right light, 4-channel output relay red and green status lights; Configurable warning yellow indicator light.

Definition of hardware slots and terminals

The overall slot configuration is fixed, with only the # 1 power IO slot and # 7CT current slot as standard, and the rest of the slots are vacant:

Slot # 1 (terminals 1-28: power supply+digital input+relay output)

Power supply: 1=24V+, 2=0V;

Status relay (3/4/5): normally closed point for monitoring machine faults;

5 programmable relays R1~R5250VAC 8A, each NO/NC common terminal;

5-way optocoupler digital DI: differential trip locking, alarm reset, 3-channel custom input, common terminal 28.

Slot # 7 (Terminal 98~109.6 CT input)

I1L1/L2/L3: Generator/motor winding terminal CT (primary side);

I2L1/L2/L3: Neutral point/transformer side CT (secondary side);

Each CT S1 (k) and S2 (l) standard polarity terminal.

CT primary standard wiring scheme

Star connection method (commonly used for generators)

The three-phase CT at the machine end and the three-phase CT at the neutral point are connected to MDR-2 I1/I2 at the same end, and can be grounded to either end of S1/S2.

2 triangle connection method (triangle winding motor/transformer)

The rated current on the nameplate is divided by √ 3 to set the rated current of the device, and the CT polarity is strictly matched to prevent unbalanced differential current misoperation.

3 DC circuit wiring

24V power supply, locking input, alarm reset input, and independent output of five trip/alarm relays can drive the generator circuit breaker, AVR demagnetization, and sound and light alarm separately.

Complete parameter tuning system

Supports two configuration methods: local panel password operation, PC Multi line upper software, all parameters with unique menu numbers, and hierarchical permission protection.

1. Core parameters of differential protection

Alarm group (1010 series): Y1W/Y2W fixed value, action delay, output relay selection, on/off switch; Factory Y1W=20%, Y2W=55%, delay of 0.1s;

Trip group (1020 series): inflection point X1, Y1T/Y2T, delay, trip output; Factory X1=100%, Y1T=25%, Y2T=70%, delay of 0.1s;

Fixed trip (1030): 100%/85% differential current interruption, with a minimum delay of 0.05s;

Trip circuit suggestion: trip the generator outlet circuit breaker on one side and cut off the AVR excitation on the other side to avoid continuous power supply and winding damage caused by faults.

2. General System Parameters

Rated setting (4010): Rated current 1~10000A, 48~62Hz; The triangulation method needs to be divided by √ 3;

CT ratio (4020): primary edge 5-10000A, secondary edge 1A/5A;

3 Battery undervoltage alarm (4220): 8-24V threshold, delay, alarm output;

4 Clock: Year/Month/Day/Hour/Day mobile settings, power-off memory;

5 languages: English/German/French/Spanish are available for selection;

6. User password: Factory 2000, customizable from 0 to 32000;

Automatic alarm reset: 0.1-10s delay switch;

8 Service menu: JUMP direct access, real-time viewing of DI/DO status, remaining alarm delay, used for on-site investigation.