Basler Electric BE3-37, BE3-51, and BE3-37/51 Ac Current Relay

INTRODUCTION

BE3 ac current relays provide current monitoring and protection in

both single-phase and three-phase systems. They are used in

applications such as motor protection, load detection, and generator

control. Undercurrent, overcurrent, and combined over/undercurrent

units are available. BE3 ac current relays operate when the

adjustable trip point is reached. A time delay control is provided with

an adjustment of 0 to 10 seconds (relay operating time is typically

200 milliseconds). This time delay may be used to prevent false

tripping when there are slight variations in the sensed current.

On overcurrent units, the output relay energizes when the input

signal exceeds the trip point. On undercurrent units, the output relay

de energizes when the input signal goes below the trip point. A red

LED indicates the state of the output relay. A green LED indicates

the condition of the power supply.

OPERATION

BE3-37 and BE3-51 ac current relays have two external, user

adjustable controls marked SET and DELAY. The BE3-37/51 has

four controls: UNDER SET, UNDER DELAY, OVER SET, and

OVER DELAY. The SET control adjusts the relay trip point. An

overcurrent trip causes the relay output to energize when the

current rises above the SET threshold. The overcurrent SET level is

adjustable from 40 to 120% (±3%) of nominal input. An undercurrent

trip causes the relay output to de-energize when the current

decreases below the SET threshold. The undercurrent SET level is

adjustable from 0 to 80% (±3%) of nominal input. Time delay is the

amount of time that elapses after the trip point is reached and when

the output relay operates.

Setting Example

A BE3-51 relay has the following settings:

SET - 120%

DELAY - 4 seconds

A trip occurs when the sensing current rises above six amperes for

four seconds. Reset occurs when the current decreases below 5.75

amperes (5% of nominal below trip setting).

INSTALLATION

BE3 ac current sensing relays are designed for mounting on

standard DIN rails that comply to DIN-EN 50022. Mounting involves

hooking the top edge of the cutout on the base of the case over one

edge of the DIN rail. The opposite side of the cutout containing the

release clip is then pushed over the opposite side of the DIN rail. To

remove or reposition the relay, lever the release clip and move the

relay as required. BE3 relays should be installed in a dry, vibration

free location where the ambient temperature does not exceed the

operating temperature range. Connections to the relay should be

made using wire that meets applicable codes and is properly sized

for the application. Figure 1 shows the terminal connections for the

BE3-37. BE3-51. and BE3-37/51 ac current relays.