YASKAWA GA80U4720ABM, Manual

Page: 119 / 1016

Electrical
Installation
3
3.11 Dynamic Braking Option, Motor Protection
YASKAWA SIEPC71061737B GA800 Drive Technical Reference 119
motor to overheat when the load current is in the motor rated value. Enable the electronic thermal protection in the
drive when possible to prevent this problem.
The electronic thermal overload function uses the relation between the speed and heat characteristics in the variable
speed control range to simulate the cooling ability of general-purpose motors and forced-vented motors to prevent
damage to the motor.
When You Operate More than One Motor with One Drive
To disable the overload protection function of the electronic thermal protector of the drive, set L1-01 = 0 [Motor
Overload (oL1) Protection = Disabled] .
Note:
If you operate more than one motor from one drive, you cannot use the electronic thermal protection of the drive.
Length of the Motor Cables
If you use long motor cables with a high carrier frequency, the increased leakage current can cause nuisance tripping
of the thermal relay. To prevent this, decrease the carrier frequency or increase the tripping level of the thermal
overload relay.
Nuisance Tripping Because of High Drive Carrier Frequency
High carrier frequency PWM drives make current waveforms that can increase the temperature in overload relays. It
may be necessary to increase the trip level setting when encountering nuisance triggering of the relay.
WARNING! Fire Hazard. Before you increase the detection level of the thermal relay, make sure that a secondary problem is not the
cause of the overload. Make sure that you know the local codes for electrical wiring, then adjust the electrothermal settings.
Incorrect thermal relay adjustment and incorrect wiring can cause serious injury or death.