GE AV-300i, Руководство пользователя, Страница: 36 / 296

GEH-6641E
—————— Function Description ——————
36
Ch.1
1.3.2.7 Control of the Motor Overload (Overload Contr)
The Overload control function is based on a I 2 t. Three independent control types are supplied:
for the protection of the Drive, of the motor and of the BU (Brake unit) against thermal overloads.
1.3.2.7.1 I
2
t Protection Against a Drive Overload
The I
2
t protection on the Drive is set to allow the IEC 146 service class 2
The integrator acts according to the following formula:
Drv OL accum %=
∫
(I 2 -I
CONT
2 ) . dt
Where I
CONT
is the direct current supplied by the Drive (consider the derating factors).
A restriction for the 0...3 Hz frequency fields is applied (see the note below)
A short overload of 200% (I2N output rated current according to IEC 146 Class 2) is possible for 0.5 seconds
each 60 seconds.
The Drive protection logic reduces the current limit to the I
CONT
value when the integrator times out. It is possible
to configure the action of the alarm signal (see Alarm Block), default setting also causes the drip to fault.
The current limit is automatically reset when the accumulator goes back to zero.
The following variables are available as digital signals:
Drv OL trip It states that the trip condition of I 2 t has been reached.
Drv OL warning It states that I
2
t has reached 90%
Drv OL accum % It states the condition, as a percentage, of the Rms current integration.
100 % = alarm level I
2
t
Overload time
Pause time