15 UL Standards
YASKAWA TOEPC71061752B GA500 Drive Installation & Primary Operation 183
The overload tolerance decreases as motor speed decreases because the cooling fan speed
decreases and the ability of the motor to cool decreases in the low speed range.
The overload tolerance characteristics of the motor change the trigger point for the electronic
thermal protector. This provides motor overheat protection from low speed to high speed across
the full speed range.
Load Tolerance Cooling Capability
Overload Characteristics
(at 100% motor load)
This motor is designed to operate with
commercial line power. Operate at a 50
Hz base frequency to maximize the
motor cooling ability.
If the motor operates at frequencies less
than commercial line power, the drive
will detect oL1. The drive triggers a
fault relay output and the motor coasts
to stop.
■ L1-02: Motor Overload Protection Time
No.
(Hex.)
Name Description
Default
(Range)
L1-02
(0481)
Motor Overload
Protection Time
Sets the operation time for the electronic thermal protector of the
drive to prevent damage to the motor. Usually it is not necessary to
change this setting.
1.0 min
(0.1 - 5.0 min)
Set the overload tolerance time to the length of time that the motor can operate at 150% load
from continuous operation at 100% load.
When the motor operates at 150% load continuously for 1 minute after continuous operation at
100% load (hot start), the default setting triggers the electronic thermal protector.
Figure 15.3 shows an example of the electronic thermal protector operation time. Motor
overload protection operates in the range between a cold start and a hot start.
This example shows a general-purpose motor operating at the base frequency with L1-02 set to
1.0 min.
• Cold start
Shows the motor protection operation time characteristics when the overload occurs
immediately after starting operation from a complete stop.
• Hot start
Shows the motor protection operation time characteristics when overload occurs from
continuous operation below the motor rated current.
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