Basler BE1-50/51B-255 Replacement CO Relay Guide

6.6 50-B Instantaneous Start Value Test

The setting value of 50-B is set through the SW9/SW10 at the top of the movement. This step tests the 2.0A and 8.0A gears in sequence

The verification value is the same standard as the 50-A test (starting value ± 2% ± 25mA)

6.7 Target indication test

Connect the DC power supply to the output contact circuit according to Figure 5-2

Apply 2Aac induced current to close contact 51, slowly increase the DC power supply to the target action - verify that the action is within the jumper setting range

50-A target similarity test

6.8 HLT functional testing

50-B set value=2.0A, HLT switch on

Apply 3Aac induced current → 1-10 contacts should not close

Close the HLT switch, and the HLT indicator light should light up

Apply 3Aac induced current → 1-10 contacts should be closed immediately

6.9 Manual Trip Test

Warning: The front panel test socket has a tripping circuit voltage, and insulation jumper must be used during testing.

Apply 0.9Aac (provide working power but below startup threshold)

Short circuit the 51 manual trip socket → Verify that the timer detects the closure of the 51 contact

Short circuit the 50-A manual trip socket → Verify that the timer detects the closure of the 50-A contact

Characteristic curve and setting calculation

7.1 Timing characteristic equation

The timing characteristics of BE1-50/51B-255 are defined by the following equation:

T_T = A·D / (M^N − C) + B·D + K

T: Action time (seconds)

D: Time dial setting value

M: Multiple of current relative to the starting value

A. B, C, N, K: constants of specific curves (see Table 7-1/7-2)

The constant selects the curve family (ABB CO type or GE IAC type) through switch SW3-3, covering a range of 1.3-40 times the starting value.

7.2 Integral reset equation

T_R = R·D / (M² − 1)

TR: Reset time (seconds)

R: Curve specific constant

D: Time dial setting value

M: Current multiplier during reset period (M=0 when it drops to 0, negative value indicates complete reset)

7.3 Coordination and Cooperation Calculation Example

In a typical feeder protection coordination scheme, if BE1-50/51B-255 adopts ABB CO-11 inverse time limit curve, the cumulative effect of action time during multiple reclosing processes can be calculated using the integral reset characteristic when cooperating with upstream electromagnetic relays. When D is set to 2, the full action time at 10 times the startup value is 0.209 seconds, and the full reset time is 15.5 seconds. If there is a coincidence 3 seconds after the first trip, the second action time is only 0.040 seconds; The third time (cumulative reset time 11.96 seconds) is 0.161 seconds, fully reflecting the engineering value of the integral reset characteristic in the reclosing coordination.

Common troubleshooting guide

Troubleshooting direction

ACTIVE/PICKUP LED does not light up. Check if the induced current is less than 0.5A (minimum LED lighting current); Is the CT circuit open or wired incorrectly

Check if the TIME PICKUP set value is much higher than the actual current when the LED green to red does not convert; Is the startup value set accurately

Confirm whether the selection of the SW3-3 curve family is consistent with the curve graph used when the timing action time deviation exceeds the tolerance; Does the TIME DIAL dial correspond to the correct position; Test whether the current is a precise multiple

Check if INST PICKUP is mistakenly set to 00 (which will affect timing calibration) during the 50-A momentary inactivity check; Has the induced current reached the set value; SW3-2 delay switch status

Is the HLT switch closed when the 50-B does not operate; Is the starting value of 50-B higher than the actual current; Is the SW9/SW10 setting accurate? (Note that A~F correspond to 10~15A)

Check if the J1/J2 jumper position matches the tripping circuit current level (80~200mA or 0.9~2.25A) when the target does not move; Does the output circuit current meet the minimum requirements

Whether the gravity self-locking target does not reset and the target reset button is pressed properly; Is the mechanical mechanism jammed

After replacing the ABB relay, if it does not close, confirm whether the blade switch of the new relay has been tightly closed; Is the panel locking nut securely in place; Has the CT short-circuit reset when the old relay is pulled out

Check if the SW3-3 position (OFF=ABB CO type, ON=GE IAC type) is consistent with the matching logic for abnormal coordination with GE relays