Beckwith Electric M-3425A Generator Integrated Protection Relay

Beckwith Electric M-3425A Generator Integrated Protection Relay

Product Overview

Positioning: Integrated generator protection system, covering internal faults of the generator, external faults of the system, and various abnormal working conditions, supporting main protection, backup protection, and abnormal alarm.

Hardware form: Standard 19 inch rack mounted, also supports vertical panel installation; It is divided into two hardware versions: standard I/O and extended I/O.

Standard I/O: 6 control status inputs, 8 programmable output contacts;

Expansion I/O (optional): Add an additional 8 inputs and 15 outputs, with all A-type contacts for output;

Sampling input: 5 voltage inputs; 7-channel current input, CT supports 1A/5A secondary two specifications;

Power supply: Wide AC/DC power supply; Optional redundant power supply; Expansion I/O models come standard with dual power supplies;

Time synchronization: supports IRIG-B (modulation/demodulation) time synchronization, achieving millisecond level timestamps for events;

Supporting option module

Function of optional module

M-3931 HMI human-machine interface 2-line x 24 character vacuum fluorescent display screen+buttons, local browsing, modifying settings, viewing events, three-level password permission

The M-3925A Target alarm indicator module has 24 protection action LED indicators and 8 output status LEDs, which intuitively display which protection component is in action

M-3921 excitation grounding coupler is used in conjunction with 64F/64B excitation grounding/brush lifting protection to isolate excitation high-voltage DC

M-3801D IPSplot PLUS waveform recording data analysis software, analyzes COMTRADE/BECO format recording files

Communication Interface

COM1: Front panel RS-232; COM2 backplane RS-232; COM3 backplane RS-485;

Optional RJ45 Ethernet, supporting Modbus TCP, BECO2200 TCP, IEC 61850;

Equipped with S-3400 IPScom PC software, used for constant value reading and writing, real-time measurement, waveform recording download, and event reading.

Storage and recording capabilities

Fault Target Record: Save the last 32 tripping events with timestamps, record the operating components, input/output status, and phase/neutral point current at the time of the fault; Lost due to power outage.

Event sequence recording SOE: up to 512 entries, 1ms time resolution; Lost due to power outage.

Fault waveform recorder: sampling rate 16 times the power frequency; The maximum total length is 416 cycles, which can be divided into 1-16 segments for storage; Support pre triggering and post triggering; Output standard COMTRADE or BECO private format; All data recorded during power outage is lost.

Featured features: IPSigmic programmable Boolean logic built-in logic engine, using input contacts, protecting component action states, and implementing up to 6 sets of custom logic through AND, OR, NOT, and timers to drive output contacts and switch constant value groups.

Four fixed value groups: Four complete fixed value configurations, which can be switched through HMI, communication, external contacts, and IPSigmic; The relay pauses protection for about 1 second during the switching process.

Protection function grouping (ANSI device number)

1) Base package (standard)

Brief description of the full name of ANSI number protection function

24 over excitation V/Hz definite time/inverse time overcurrent protection to prevent overexcitation of the generator core

27 phase low voltage three-stage undervoltage protection

32 directional power with three fixed values of directional power; Reverse power (to prevent motor drag), low forward power, and over power; Can be used for sequential tripping

40 demagnetization protection dual zone offset Moho circle; Low voltage control can be used to accelerate tripping

46 Negative sequence overcurrent sensitive Negative sequence overcurrent, inverse time limit/definite time limit, to cope with unbalanced loads and non full phase

50 phase instantaneous overcurrent phase current quick break

50/27 Mis power on protection: Generator not connected to the grid with live closing protection (overcurrent+low voltage)

50BF circuit breaker failure protection, generator switch failure protection

50N instantaneous overcurrent neutral line current quick break

51N neutral point inverse time overcurrent neutral point inverse time grounded overcurrent, supporting IEC/IEEE curve family

51V with voltage control/voltage limitation three-phase inverse time overcurrent backup overcurrent, voltage suppression/voltage control

59 phase overvoltage three-stage overvoltage protection

59N neutral point overvoltage neutral point zero sequence overvoltage grounding alarm/trip

59X multifunctional overvoltage can be used for inter turn faults, bus grounding, and additional voltage input channels

60FL PT fuse detection detects PT disconnection, locks relevant voltage protection, and outputs an alarm

67N residual direction overcurrent zero sequence direction grounding protection

81 frequency protection (4-segment) 4-segment over/under frequency

87 phase differential generator phase current differential main protection

87GD grounding (zero sequence) differential zero sequence grounding differential, mainly used for low impedance grounding units

IPSigmic Programmable Logic Boolean Logic+Timer Custom Logic

2) Comprehensive package (added on top of the basic package)

Brief description of the full name of ANSI number protection function

21 Three stage phase distance protection with three zone Moho characteristics, system fault backup; Zone 3 can be used for out of step locking; Support load intrusion blocking

27TN Third Harmonic Neutral Point Undervoltage Third Harmonic Stator 100% Grounding Protection (High Resistance Grounded Generator)

49 stator overload positive sequence overcurrent, stator thermal overload protection

50DT timed overcurrent (phase differential) can be configured as split phase differential protection. When this mode is enabled, 87 and 87GD cannot be used

78 Out of Step Protection Out of Step Out of Step Detection, Sliding Pole Counting, Mjol Characteristics

81A Low Frequency Time Accumulated Low Frequency Accumulation, Accumulated Low Frequency Operating Time, Protecting Turbine Blades

81R frequency change rate ROCOF df/dt frequency slip protection

3) Optional ordering protection (requires additional procurement)

ANSI Number Protection Function Full Name Hardware Requirements Description

25 Synchronous phase check Sync Check without external hardware grid synchronization check: phase difference, voltage difference, frequency difference; Support empty bus/empty line logic; Enabling it will occupy some protection channels

64F/64B excitation grounding/brush lifting detection M-3921 coupler rotor excitation circuit grounding; Detect the lifting/poor contact of the electric brush; Injecting low-frequency square waves into the rotor to measure insulation resistance

64S low-frequency injection type 100% stator grounding protection can be achieved for 20Hz signal source, bandpass filter, 20Hz CT generator shutdown and operation status; External hardware must be ordered as a complete set; Partial grounding protection components are unavailable after activation

Important Mutual Exclusion Constraint: Some features cannot be enabled simultaneously. Example: If 64S is enabled, 50N/51N/59D/67N (I-N mode)/87GD will not be available; Enabling 25 synchronous check will disable 59X (Vx) and 67N (Vx) modes; Disable 87 and 87GD in 50DT split phase differential mode.

Hardware electrical, environmental, mechanical specifications

Working environment: Working temperature -20 ℃~+70 ℃; Damp heat at 40 ℃, 93% RH without condensation; Through IEC 60255 full EMC anti-interference: electrostatic 8/15kV, fast transient 4kV, surge, RF radiation anti-interference. Insulation withstand voltage 3500Vdc.

Contact capability: The tripping contact meets ANSI C37.90-1; Connect for 30-0.2 seconds; Continuous 8A; breaking capacity varies with voltage level.

Measurement accuracy: Voltage ± 0.5V or 0.5%; Current 5A ± 0.1A or 3%, 1A ± 0.02A or 3%; The frequency is within ± 0.02Hz around the rated range.

Mechanical dimensions

Ordinary I/O (3U rack): 483 × 132 × 259mm, weight 7.7kg;

Expansion I/O (4U rack): 483 × 177 × 259mm, weight 8.6kg;

Support installation of horizontal racks and vertical panels, with opening drawings provided in the documentation.

External supporting hardware (64S low-frequency injection)

20Hz signal generator; 20Hz bandpass filter; 400/5A 20Hz dedicated CT;

M-3921 excitation grounding coupler: isolated excitation DC up to 1200Vdc, used for grounding 64F/64B rotors.

Key usage precautions

The recording, Target, and SOE are all stored in RAM and lost during power outages. They need to be uploaded and saved to the computer's hard drive in a timely manner through software.

Multiple protection functions are mutually exclusive and need to be checked during ordering and configuration. For example, the 64S low-frequency stator grounding will disable some zero sequence protection.

Switching between fixed value groups will temporarily pause the protection logic and cannot be used for uninterrupted real-time frequent switching.

The 64S low-frequency injection stator grounding protection must be purchased as a complete set of external hardware and cannot be easily activated by software in the later stage.

HMI three-level password, factory password function disabled; Level 3 password 9999 means password protection is turned off.

IRIG-B time synchronization is a necessary condition for millisecond level event timescales; The clock does not rely on the internal clock of the machine, and its time accuracy is limited.

CT supports 1A/5A, to be confirmed at the time of ordering, hardware cannot be directly modified on-site.

Circuit breaker monitoring BM function: Accumulate arc I ² T, count the wear of circuit breaker contacts, output alarm when the threshold is reached, and prompt maintenance switch; Trip circuit monitoring TC monitors the integrity of the trip circuit.

Typical application scenarios

Complete sets of protection for various generators driven by steam turbines, water turbines, and diesel engines;

High impedance grounded generator (third harmonic 27TN/59D or 64S low-frequency injection to achieve 100% stator grounding);

Low impedance grounded generator, using 87GD grounding differential;

Grid connected generator: synchronous check 25, out of step 78, reverse power 32, accidental power on 50/27, circuit breaker failure 50BF;

Rotor protection: excitation grounding 64F, brush status detection 64B;

Implementing custom interlocking logic for power plants using IPSpeegic;

External temperature controller contacts can be connected, and temperature alarm logic can be implemented through IPSigmic.