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

Basler BE1-50/51B-255 Overcurrent Relay: ABB CO Series Direct Replacement and Engineering Application Guide

Product positioning and replacement value

The BE1-50/51B-255 overcurrent relay launched by Basler Electric is a non directional overcurrent protection device based on microprocessor design, specifically designed for phase overcurrent or ground overcurrent protection in 50Hz or 60Hz power systems. This relay is equipped with three protective components: a timed overcurrent (51) component and two instantaneous overcurrent (50-A and 50-B) components, with the 50-B component used to implement the "Hot Line Tag" (HLT) function.

The most significant application value of BE1-50/51B-255 lies in its ability to directly replace ABB (Westinghouse) CO series electromagnetic overcurrent relays. Specific compatible models include CO-2 (short inverse time), CO-5 (long inverse time), CO-6 (timed), CO-7 (medium inverse time), CO-8 (inverse time), CO-9 (very inverse time), and CO-11 (extremely inverse time). The replacement operation is extremely simple - just set the required parameters on the new relay, unplug the original ABB relay plug-in core, insert the new core, close the blade switch, and install the new panel to complete the upgrade without changing the cabinet wiring.

Compared to traditional electromagnetic CO relays, the advantages of BE1-50/51B-255 include:

Extremely low CT burden: expands the linear working range of CT

Self powered operation: obtaining working power directly from induced current

Continuous automatic calibration: no need for internal manual adjustment

Gravity self-locking target indication: maintains motion indication even after power failure

Minimum transient exceedance: The instantaneous component effectively eliminates the exceedance caused by the transient component of the fault current

Core technical specifications

2.1 Timed overcurrent (51) component

Start value setting range: 0.5~15.9Ac (0.1A step)

Startup accuracy: ± 2% ± 25mAac sum

Exit ratio: 95% of the startup value

Characteristic curve type: Following IEEE standard C37.112 (1996), simulate GE IAC, Westinghouse CO, and BS142 curves

Curve types: Short inverse time, Long inverse time, Fixed time, Medium inverse time, Inverse time, Very inverse time, Extreme inverse time, BS142 Very inverse time, BS142 Extreme inverse time, Fixed timing (0.1~9.9s)

Timing accuracy: ± 1 cycle ± 2% within the range of 2~40 times the starting value; Within the range of 1.3 to 2 times the starting value, it is ± 2 cycles ± 2%

2.2 Instantaneous overcurrent (50-A) components

Start value setting range: 1~99Aac (1A step)

Startup accuracy: ± 2% ± 25mAac sum

Exit ratio: 95% of the startup value

Additional Delay: SW3-2 Switch Selection - No Additional Delay (OFF) or 100ms Fixed Delay (ON)

2.3 Transient Overcurrent (50-B/HLT) Components

Start value setting range: 1~15.9Aac (0.1A step)

Startup accuracy: ± 2% ± 25mAac sum

Exit ratio: 95% of the startup value

Delay characteristic: fixed as no additional delay

Reset feature: Reset within 16ms when the current drops below 95% of the starting value

2.4 Current sensing input

Continuous rating: 14Ac (below 45 ℃)

1-second rated: 400Aac

Input impedance: 4.4 Ω at 0.5A, 0.2 Ω at 5.0A

Frequency response: The change in starting current caused by a variation of ± 5Hz of the rated frequency is less than 0.5%

Harmonic suppression: The suppression characteristics of odd and even harmonics are shown in Figure 6-3

Transient response: When the system time constant reaches 40ms, it exceeds less than 10%

Control panel and configuration components

3.1 Front panel control and indication (Figure 2-1)

TIME PICKUP selector (two digit DIP): Set the timed overcurrent starting current value (ampere, integer and decimal)

INST PICKUP selector (two digit dialing): Set the instantaneous starting current value of 50-A (ampere, ten digit and one digit)

CURVE selector (10 position rotary switch): Select one of the 9 inverse time characteristics or fixed timing function (F mode)

TIME DIAL selector (two digit dialing): Select the delay multiple (00~99) on the selected curve

ACTIVE/PICKUP dual color LED: Green indicates that the relay has been powered on but not started; Red indicates that the induced current exceeds the set value for timed startup

Target indicator (gravity self-locking): Each of the 51 and 50-A components is equipped with a red target indicator, which needs to be manually reset

HLT switch: enable/disable hot wire marking function

HLT indicator light (red neon light): Illuminates when HLT is enabled and there is voltage in the trip circuit

Manual trip test socket: one pair of 51 element and one pair of 50-A element (for short circuit testing)

3.2 Internal circuit board switches and jumpers (Figure 2-2)

SW3 six position sliding switch:

SW3-1: System frequency selection (OFF=60Hz, ON=50Hz)

SW3-2:50-A additional delay (OFF=no delay, ON=+100ms）

SW3-3: Curve family selection (OFF=ABB CO type, ON=GE IAC type)

SW3-4: Reset feature selection (OFF=instantaneous reset, ON=integral reset)

SW3-5/6: Not used

50-B startup value setting switch (at the top of the movement, the movement needs to be pulled out for operation):