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.