YASKAWA UAK series User Manual page 178

(2) Changing Detection Timing of Overload (Low Load) Alarm (A.720)
An overload (low load) alarm (A.720) can be detected earlier to protect the servomotor from overloading. The
time required to detect an overload alarm can be shortened by using the derated motor base current obtained
with the following equation. The detection level of the overload (high load) alarm (A.710) cannot be changed.
Motor base current × Derating of base current at detecting overload of motor (Pn52C)
= Derated motor base current
Motor base current: Threshold value of motor current to start calculation for overload alarm
Derating of base current at detecting overload of motor (Pn52C): Derating of motor base current
The following graph shows an example of the detection of an overload alarm when Pn52C is set to 50%. The
calculation for the overload of motors starts at 50% of the motor base current and then an overload alarm will
be detected earlier.
Changing the setting of Pn52C will change the detection timing of the overload alarm, so the time required to
detect the overload warning will also be changed.
As a guideline of motor heating conditions, the relationship between the heat sink sizes and deratings of base
current is shown in a graph in:
Servomotor Heating Conditions in Rotary Servomotors General Instruction in
(KAEP S800000 42).
Set Pn52C to a value in accordance with the heat sink size and derating shown in the graph, so that an over-
load alarm can be detected at the best timing to protect the servomotor from overloading.
Overload detection time
Derating of Base Current at Detecting Overload of
Motor
Pn52C
Setting Range
(2104h:2)
10 to 100
Detection curve of
overload alarm
when Pn52C = 50%
50% 100% 200%
Setting Unit
1%
8.4 Settings for Common Basic Functions
Σ
-V Series Product Catalog
Detection curve of
overload alarm when
Pn52C = 100% (factory setting)
Torque reference [%]
Position
Speed
Factory Setting When Enabled
100 After restart
Classification
Setup
8
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