5.4 Settings That Must Be Adjusted to the System
5.4.5 Motor Overload Detection Level
5-29
Detection Timing for Overload Warnings (A.910)
With the default setting for overload warnings, an overload warning is detected in 20% of the
time required to detect an overload alarm. You can change the time required to detect an over-
load warning by changing the setting of the overload warning level (Pn52B). You can increase
safety by using overload warning detection as an overload protection function matched to the
system.
The following graph shows an example of the detection of overload warnings when the over-
load warning level (Pn52B) is changed from 20% to 50%. An overload warning is detected in
half of the time required to detect an overload alarm.
Detection Timing for Overload Alarms (A.720)
If Servomotor heat dissipation is insufficient (e.g., if the heat sink is too small), you can lower
the overload alarm detection level to help prevent overheating.
To reduce the overload alarm detection level, change the setting of Pn52C (Base Current Der-
ating at Motor Overload Detection).
An A.720 alarm (Continuous Overload) can be detected earlier to protect the Servomotor from
overloading.
Note: The gray areas in the above graph show where A.710 and A.720 alarms occur.
Refer to the relevant manual given below for a diagram that shows the relationships between
the motor heat dissipation conditions (heat sink size, surrounding air temperature, and derat-
ing). You can protect the motor from overloads more effectively by setting this derating value in
Pn52C.
Chapter 2 Selection
Pn52B
Overload Warning Level
Setting Range Setting Unit Default Setting When Enabled Classification
1 to 100 1% 20 Immediately Setup
Base Current Derating at Motor Overload Detection
Pn52C Setting Range Setting Unit Default Setting When Enabled Classification
10 to 100 1% 100 After restart Setup
Overload
detection time
Detection curve for
overload warnings
when Pn52B = 50%
Detection curve for overload alarms
Detection curve for overload warnings
when Pn52B = 20% (default setting)
Torque reference (%)
200%100%
Overload
detection time
50% 100%
A.720
A.710
200%
Detection curve
for overload
alarms when
Pn52C = 100%
(default setting)
Detection curve
for overload
alarms when
Pn52C = 50%
Torque reference (%)
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