Beckwith M-3425A Relay Guide

Erroneous movement: It may be due to the stable oscillation of the system entering the circle. The delay of circle 2 can be increased or the undervoltage control (VC) can be added to accelerate only at low voltage.

4.5 Out of step protection does not operate or malfunctions

Not moving: Check if the impedance circle and blind plate settings cover the out of step trajectory; Confirm if 'Trip on MHO Exit' is enabled as needed.

Erroneous movement: Stable oscillation may be misjudged as out of step, and delay or sliding pole counting can be increased.

4.6 100% stator grounding (64S) cannot operate correctly

Check external equipment: whether the 20Hz signal source is powered, whether the bandpass filter is connected correctly, and whether the 20Hz CT is connected correctly.

Set verification: The starting values of total current and real current should be greater than the capacitor current during normal operation (usually a few milliamps). When there is no fault, the 20Hz current value of IN can be monitored through IPScom and set to 2-3 times this value.

Voltage braking: If enabled, ensure that the neutral point 20Hz voltage is less than 25V under normal conditions, otherwise braking may reduce sensitivity.

4.7 Communication Failure

Possible causes and solutions for the phenomenon

Unable to establish connection serial port parameter mismatch, cable error, relay in local mode confirming COM1/COM2 baud rate, checksum, stop bit through HMI; Use null modem cable; Exit local mode

Read data errors after connection, address conflicts, noise interference, and check address uniqueness; Use shielded twisted pair cables and ground them; Add Dead Sync Time

Ethernet is not connected, IP address is set incorrectly, DHCP is not obtained. Check the IP/Netmask/Gateway in the "Ethernet Setup". If DHCP fails, manually set it

4.8 Circuit breaker failure (50BF) not triggered

Check whether the 50BF function is enabled; Is the starting value of phase current or neutral point current set too high; Is the input of the auxiliary contact (56a) of the circuit breaker wired correctly; Is the output contact configured with a circuit breaker failure tripping circuit.

Test: Simulate a fault to activate the protection, observe whether the 50BF timer starts, and if the current does not drop below the starting value and the circuit is still closed, output after a delay.

4.9 Loss of fuse (60FL) false alarm

Reason: When a phase to phase fault occurs in the system, the negative sequence voltage increases but the negative sequence current is not large, which may be mistaken as fuse loss.

Solution: Adjust the voltage/current threshold in the internal logic of 60FL (such as I2>0.167 I1 condition); Alternatively, an external fuse loss detection contact input can be used as a lockout.

Wave recording and event recording applications

M-3425A has a built-in recorder that can store up to 416 cycles of data, with partition numbers ranging from 1 to 16. Sampling rate of 16 points per cycle. Trigger method: input contact, output contact, functional action, serial command. The data can be stored in COMTRADE format and analyzed using IPSplot Plus.

Debugging technique: Before the first grid connection, IPScom can be used to manually trigger the waveform recording and observe whether the voltage and current waveforms are symmetrical and the phase sequence is correct. After the protection action, call the oscillograph file to analyze the fault type and action sequence.

Maintenance suggestions

Regular self check: Check the "Error Codes" and "Checksums" through HMI to confirm that there are no abnormalities.

Battery: The real-time clock uses a lithium battery. If it stops (displaying 80 seconds), it needs to be replaced (please contact the factory).

Firmware upgrade: Use IPScom's "Tools/Firmware Update" to perform the upgrade, and be sure to save the firmware file before upgrading.

Cleaning: Keep the panel and ventilation holes clean, and check the condition of the electrolytic capacitors every 5 years.

Calibration: It is recommended to verify the accuracy of voltage and current measurement with a standard source every year, and if necessary, perform "Auto Calibration" (to enter diagnostic mode).