Yaskawa Sigma-5 User Manual: Design and Maintenance - Rotary Motors - Manual (Page 108)

4.2 Settings for Common Basic Functions
4-25
Operation
(2) Changing Detection Timing of Overload Alarm (A.720)
An overload alarm (continuous overload) can be detected earlier to protect the motor 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 (instantaneous overload) alarm (A.710) can-
not 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 alarm 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 Σ -V Series Product Catalog
(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 motor from overloading.
Note: For details, refer to Overload Characteristics listed in the section for the relevant servomotor in the Σ -V Series
Product Catalog (KAEP S800000 42).
Pn52C
Derating of Base Current at Detecting Overload of Motor
Classification
Setting Range Setting Unit Factory Setting When Enabled
10 to 100 1% 100 After restart Setup
Detection curve of
overload alarm when
Pn52C=100% (factory setting)
Detection curve of
overload alarm
when Pn52C=50%
Torque reference [%] 50%
Overload detection time
100% 200%
Speed Position Torque