Selection and commissioning of Basler BE3-25 synchronous inspection relay

If any condition is not met, the output will be disconnected and the closing circuit will be locked.

3.2 Definition of Wiring Terminals (Refer to Manual Diagram)

The manual provides a terminal connection diagram (but the text does not list the terminal numbers in detail), which generally includes:

GEN input: L1, L2 (or single-phase) connected to the PT secondary side of the generator.

BUS input: L1 and L2 are connected to the PT secondary side of the bus.

Output contacts: normally open (NO), common (COM), normally closed (NC) are used to control the closing circuit.

Grounding terminal: The shell is grounded.

Key wiring rules:

Phase polarity: It is necessary to ensure that the same polarity of the generator and bus voltage is consistent, otherwise the phase comparison will be offset by 180 °, resulting in the relay never closing.

Voltage range selection: If the input voltage exceeds the nominal value (such as measuring 120V with 240V gear), the amplitude comparison will be invalid, and the correct jumper or corresponding voltage model should be ordered.

Dead bus function (- ***** 5 type): When the bus voltage is below about 10%~20% of the nominal value, the internal logic of the relay automatically ignores amplitude/phase comparison and only detects that the generator voltage is normal before closing the output. At this point, it is necessary to confirm the definition of the "dead busbar" condition on site to avoid accidental closing.

On site tuning and debugging steps

4.1 Reasonable setting of phase angle window

The setting of the phase angle window needs to be coordinated with the closing time of the circuit breaker. For example:

The inherent closing delay of the circuit breaker is 100ms.

If the system slip frequency is 0.2Hz (i.e. cycle 5s), the phase angle changes by about 7.2 ° within 100ms.

To ensure that the phase angle at the moment of closing is less than 5 °, the window can be set to 12 °~15 ° (corresponding to the adjustment knob indicating about 20%~25% position).

Operation method: Use a phase meter or oscilloscope to measure the zero crossing difference between the generator and the bus voltage. Slowly adjust the "Phase Angle" potentiometer on the panel to ensure that the relay is reliably engaged at the target angle. The factory default is usually 20 ° (corresponding to 30% position), and on-site adjustments should be made according to the actual circuit breaker speed.

4.2 Voltage difference verification

Due to the fixed voltage difference of 5%, if the no-load voltage of the generator deviates from the bus by more than this value, the relay will not be able to operate. At this point, it is necessary to adjust the generator AVR (Automatic Voltage Regulator) to match the voltage. If the bus voltage fluctuates greatly (such as with load changes), it is recommended to install a voltage regulator on the bus side or use a wide range relay (BE3 series has other models).

4.3 Dead Bus Function Test (Only for - ***** Type 5)

Disconnect all power sources on the busbar side and confirm that the residual voltage of the busbar is below 10% of the nominal value.

Start the generator and establish the rated voltage.

Observe whether the relay closes the output within a few seconds (the typical response time may be longer as the internal bus needs to be checked for no voltage).

If it is not closed, check if there is still induced voltage in the busbar side wiring (possibly caused by PT reverse power transmission), and if necessary, parallel appropriate resistors at the busbar input end to dissipate residual charge.

4.4 System joint debugging after tuning

After completing the single machine test, it should be linked with the speed controller and excitation regulator for actual parallel testing. Use a waveform recorder to record the impulse current at the moment of closing. If the impulse current is less than 1.2 times the rated value, the setting is appropriate; If the impact is too large, it is necessary to reduce the phase window or decrease the slip (adjust the governor).

Common fault phenomena and troubleshooting methods

Possible causes and solutions for the fault phenomenon

The relay always does not close, even if the voltage frequency is similar. ① The phase polarity is reversed; ② Voltage difference>5%; ③ If the frequency difference is too large (not internally locked), use an oscilloscope to check the GEN and BUS waveforms and confirm polarity; Measure the actual effective value difference; Measure the frequency difference with a frequency meter (should be<0.3Hz)

After the relay is closed, it immediately opens and shakes frequently. ① The sliding difference approaches the critical value, causing the window to enter and exit intermittently; ② Voltage fluctuations cause the difference to oscillate at the 5% boundary, reducing the slip of the governor (lowering the adjustment rate); Increase voltage filtering capacitor (consult manufacturer)

-****Type 5 dead busbar function failure ① There is still residual voltage (>10%) on the busbar side; ② Check if there is reverse power transmission on the busbar side due to insufficient voltage of the generator, or connect a discharge resistor in parallel; Confirm that the output voltage of the generator meets the standard