Areva MiCOM P225, Technical Manual

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User Guide P225/EN FT/B11
MiCOM P225 Page 33/52
•
Before the end of the T
reacc
time-delay (duration of the voltage sag shorter than T
reacc
),
the voltage is back (voltage greater than "Restoration V Dip"), but the current
absorbed by the motor does not cross the I
stall
threshold within 5 seconds after this
restoration, then:
−
the P225 relay operation does not change.
•
At the end of the T
reacc
time-delay, the voltage drop is still present (duration of the
voltage sag greater than T
reacc
), then:
−
a VOLTAGE DIP signal is issued by the P225 relay. Assigning this signal to the
trip output relay (RL1) allows to stop the motor if required.
Examples
Case n°1:
The duration of the voltage drop is less than the T
reacc
time delay, when the mains voltage is
restored, re-acceleration of the motor is authorised.
P0237ENa
Network/mains
voltage
Voltage sag
Current
flowing into
the motor
Motor
reacceleration
T
reacc
“Drop in voltage” condition detected by P225 relay
(internal logic signal)
t I
start
Reacceleration authorization
I
stall
>threshold
“ stalled rotor whilst running” function active
Fixed window of 5 s
“ stalled rotor whilst running”
function deactivated
Detection
V dip threshold
Restoration V dip
threshold