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

SW9 (16 bits): Set integer values (0~9 corresponds to 0~9A, A~F corresponds to 10~15A)

SW10 (10 bits): Set the decile (0~9 corresponds to 0.0~0.9A)

Target operating current jumper (J1/J2):

Crossing 1-2 pins: minimum operating current of 0.9~2.25A

Cross connect 2-3 pins: minimum operating current 80~200mA

Function description and working principle

4.1 Signal Process (Figure 3-1)

The single-phase AC current provided by the system CT is connected to the relay through terminals 8 and 9, and supplied to the power CT and signal CT respectively. The output of the power CT is rectified and filtered to provide working power for all circuits, with one precise 5VDC output serving as an automatic calibration reference.

The current output from signal CT is rectified and sent to three independent proportional resistor networks, which are controlled by the 51, 50-A, and 50-B starting value selection switches. The analog-to-digital converter converts the analog voltage on the proportional resistor into a digital signal and sends it to the microprocessor.

The microprocessor performs program operations based on induced current, switch settings, and internal software. When the induced current exceeds the TIME PICKUP set value, the ACTIVE/PICKUP LED changes from green to red, and the 51 timing element counts according to the characteristic curve equation; When the induced current exceeds the set value of INST PICKUP, the 50-A output contact immediately closes; When the induced current exceeds the set value of 50-B and the HLT switch is closed, the output contact of 50-B is closed.

4.2 Integral reset characteristics

The integral reset characteristic simulates the "disc reset" behavior of electromagnetic relays, starting timing when the current drops below 95% of the starting value, and continuing to work even if the current completely drops to zero. The reset time equation is:

T_R = R·D / (M² − 1)

Among them, TR is the reset time (seconds), R is the curve constant, D is the set value of the time dial, and M is the multiple of the current relative to the starting value. This feature is particularly important when used in conjunction with electromagnetic relays with thermal memory effects - it ensures that the relay "remembers" the accumulated heat from the previous fault during multiple reclosing processes, thereby achieving more accurate selective coordination.

Installation and wiring points

5.1 Directly Replace Installation Steps

Select the desired protection settings on the new BE1-50/51B-255

Pull out the core of the original ABB (Westinghouse) CO relay

Insert the new relay core and lock it in place

Close the blade switch

Install the new panel and secure it with the panel locking nut

5.2 Electrical Connections (Figure 4-1, 4-2)

Communication input: terminals 8 and 9 (current sensing input, 5A CT circuit)

51/50-A/50-B output contacts: terminals 1 and 10 (common trip output)

DC control circuit: see Figure 4-2 for typical wiring

When replacing the relay, due to the fact that all current input terminals of the BE1-50/51B-255 module are equipped with short-circuit wires when unplugged, it can ensure that the CT circuit does not open during the unplugging process, without the need for additional short-circuit operations.

5.3 Target Operating Current Setting

The target indicators for both the 51 component and the 50-A component are current excitation type, and their respective minimum operating current ranges can be set through circuit board jumpers J1 and J2 to adapt to different levels of trip circuit current.

5.4 Storage and Maintenance

The device contains long-life aluminum electrolytic capacitors inside. For long-term storage of backup equipment, it is recommended to run it on power for 30 minutes every year to extend the lifespan of the capacitor.

Complete on-site testing process

6.1 Testing Equipment Requirements

0~20Aac current source (induced input current)

DC power supply (target operation test)

Timer or counter

6.2 51 Component Startup Value Test

Connect the test circuit according to Figure 5-1

SW3-3=OFF (ABB curve), SW3-4=ON (integral reset)

Apply current to the ACTIVE/PICKUP LED turning red - the starting current should not exceed 0.55Aac

Reduce the current until the LED turns from red to green and then goes out

Set TIME PICKUP=2.2, slowly increase the current until the LED turns red - the current should be between 2.131 and 2.269Aac

6.3 Timing accuracy test

TIME PICKUP=1.0，TIME DIAL=4.5，CURVE=S

Apply 1.5Aac (1.5 times the starting value) and time until the 51st contact is closed

The timing value should be between 0.345 and 0.424 seconds (this tolerance is the cumulative starting and timing tolerance)

6.4 Integral Reset Test

TIME DIAL=9.9，CURVE=V，TIME PICKUP=1.0

Apply 4.0Aac to the relay and remove the current for 29 ± 0.25 seconds

Apply 4.0Aac again and time until the second action - it should be 2.08 ± 0.4 seconds

6.5 50-A Instantaneous Start Value Test

TIME DIAL=0.0，CURVE=S，TIME PICKUP=15.0

Set INST PICKUP=02, slowly increase the current to close the 50-A contact - the current should be between 1.935 and 2.065Aac

Set INST PICKUP=08, increase current to contact closure - current should be between 7.815~8.185Ac