Basler Electric BE3-47N and BE3-47N/27 Phase Balance Relay

INTRODUCTION

BE3-47N phase balance relays protect three-phase lines,

transformers, motors, and generators against phase

unbalance, phase loss, and phase reversal. BE3-47N/27

relays have the added feature of undervoltage protection.

The output relay energizes and the red RELAY LED lights

when a balanced input with the proper phase sequence is

sensed. The output relay de-energizes and the RELAY LED

goes out when a fault condition is detected. The green

POWER LED indicates the condition of the power supply.

Two external controls are provided: UNBAL (unbalance) and

DELAY. The UNBAL control adjusts the percentage of

unbalanced voltage at which the relay trips. The DELAY

control provides an adjustable time delay to prevent tripping

on voltage transients.

OPERATION

The BE3-47N and BE3-47N/27 phase balance relays have

two external, user-adjustable controls marked UNBAL and

DELAY. The UNBAL control adjusts the relay trip point. The

relay trips when the voltage becomes unbalanced by the

percentage set by the UNBAL control. The trip point is

adjustable from 5 to 15% (±5%) of nominal input. The

DELAY control adjusts the time from when a fault is

detected until the output contacts change state. The delay is

adjustable from 0 to 10 seconds. The undervoltage feature

of the BE3-47N/27 has no external adjustment and is fixed

at 85% of the nominal input voltage. If all three phases

remain balanced, but decrease below 85% of nominal

voltage, the relay de-energizes.

Settings Example

A BE3-47N/27 relay with a nominal input rating of 120 Vac

has the following settings:

• UNBAL - 10%

• DELAY - 5 s

The relay detects a phase unbalance when any one phase

decreases to 108 Vac or increases to 132 Vac. The output

relay trips five seconds after the phase unbalance is

detected. The output relay also trips if all phases decrease

to 85% of nominal, or 102 Vac.

INSTALLATION

BE3 phase balance 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 BE3-47N/27 relay. Connections

for the BE3-47N relay are identical.

CALIBRATION

The calibration marks on the faceplate have a maximum

error of 10% and are provided only as guides. Proper

calibration requires using an accurate voltmeter in parallel

with the input signal. Use the following procedure to

calibrate your relay.

Unbalance

1. Adjust the UNBAL control fully clockwise and the

DELAY control fully counterclockwise.

2. Apply three-phase, nominal input voltage with the

proper phase sequence to the relay. The output relay

should energize.

3. Lower one phase of the applied voltage to the desired

trip level. Slowly adjust the UNBAL control

counterclockwise until the relay trips.

Delay

1. Set the DELAY control at the desired time setting.

2. Apply three-phase, nominal input voltage with the

proper phase sequence to the relay.