Lenze EVF9338 - Manual (Page 66)

Safety instructions
Thermal motor monitoring
Description
2
l
66 EDKVF9338 DE/EN/FR 4.0
2.2 Thermal motor monitoring
2.2.1 Description
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Note!
From software version 8.1 onwards, the 9300 vector controllers are provided
with an I
2 xt function for sensorless thermal monitoring of the connected
motor.
ƒ I 2 xt monitoring is based on a mathematical model which calculates a
thermal motor utilisation from the detected motor currents.
ƒ The calculated motor utilisation is saved when the mains is switched off.
ƒ Nevertheless, I 2 xt monitoring does not provide full motor protection
because other influences on the motor utilisation such as changes in the
cooling conditions (e.g. cooling air flow interrupted or too warm) cannot be
detected.
The I 2 × t−load of the motor is constantly calculated by the drive controller and displayed
in C0066.
The I 2 x t−monitoring is designed in a way, that a motor with a thermal motor time factor
of 5 min, a motor current of 1.5 x I
r
and a trigger threshold of 100 % releases the
monitoring after 179 s.
You can set different reactions with two adjustable trigger thresholds.
ƒ Adjustable reaction OC8 (TRIP, Warning, Off).
– The reaction is set in C0606.
– The trigger threshold is set in C0127.
– The reaction OC8 can be used for example for an advance warning.
ƒ Fixed reaction OC6−TRIP.
– The trigger threshold is set in C0120.
Response of the I 2 x t−monitoring Condition
The I 2 x t−monitoring is deactivated.
C0066 = 0 % and
MCTRL−LOAD−I2XT = 0,00 % is set.
Set the controller inhibit at C0120 = 0 % and
C0127 = 0 %.
The I 2 x t−monitoring is stopped.
The actual value in C0066 and at the MCTRL−LOAD−I2XT
output is held.
Allow controller release at C0120 = 0 % and
C0127 = 0 %.
The I 2 x t−monitoring is deactivated.
The motor load is displayed in C0066.
Set C0606 = 3 (Off) and C0127 > 0 %.
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Note!
An OC6 or OC8 error message can only be reset if the I 2 × t−monitoring has
fallen below the set trigger threshold by 5 %.