| The M200-PB1 can detect
the following conditions in 3 phase 3 or 4 wire systems.
Phase unbalance, Phase loss, Phase Reversal, Phase
Sequence. The phase balance relays are used to detect
phase loss and unbalance in systems using motors,
generators, heater elements, transformers etc. A phase
unbalance as small as 10% in a 3 phase motor can cause
the temperature in the motor winding to increase by more
than 120%, correct setting of the PB1/PB2 will ensure
that this does not occur. Protection against open phase
regenerated voltage created if a single phase
should fail is also provided. Customer adjustment of
unbalanced voltage between 5 to 15% is provided along
with time delay adjustment of 200mS to 10 seconds. If the
system being monitored is healthy, the relay is
energised, red LED illuminated, if there is a phase
unbalance greater than the preset level or phase
loss/reversal occurs, the relay de-energises after the
time delay period. The M200-PB2 provides all the
protection features of the PB1 with the additional
benefit of having symmetrical under voltage protectgion.
This means that if all 3 phase voltages remain balanced,
but drop below a preset voltage, the relay will
de-energise. The under voltage is internally set, for
standard units it is set at 85% below the nominal voltage
but this value can optionally be between 70 and 90%. |
