Basler Electric BE3-27T, BE3-59T, and BE3-27T/59T Ac Voltage Relay

INTRODUCTION

BE3 ac voltage relays provide voltage monitoring and protection in

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

applications such as utility mains failure, regulation of power

supplies, and to protect voltage sensitive equipment. Undervoltage,

overvoltage, and combined over/undervoltage units are available.

BE3 ac voltage relays operate when the adjustable trip point is

reached. An external 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 voltage supply. 

On overvoltage units, the output relay energizes when the input

signal exceeds the trip point. On undervoltage units, the output

relay de energizes when the input signal goes below the trip point.

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

the condition of the power supply.

OPERATION

BE3-27T and BE3-59T ac voltage relays have two external, user

adjustable controls marked SET and DELAY. The BE3-27T/59T has

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

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

overvoltage trip causes the relay output to energize when the

voltage rises above the SET threshold. The overvoltage SET level

is adjustable from 100 to 125% (±3%) of nominal input (Vnom

). An

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

voltage decreases below the SET threshold. The undervoltage SET

level is adjustable from 75 to 100% (±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 BE3-59T relay with a nominal input rating of 240

Vac has the following settings:

• SET - 120%

• DELAY - 4 seconds

A trip occurs when the sensing voltage rises above 288 Vac and 4

seconds elapses. Reset occurs when the voltage decreases below

285.6 Vac (1% of nominal below setpoint).

INSTALLATION

BE3 ac voltage 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

BE3-27T, BE3-59T, and BE3-27T/59T relays.