3. Characteristics
3 - 3
3-1-2 Overload protection characteristics
The servo drive unit has an electronic thermal relay to protect the servomotor and servo drive unit from
overloads. The operation characteristics of the electronic thermal relay are shown below when standard
parameters (SV021=60, SV022=150) are set.
If overload operation over the electronic thermal relay protection curve shown below is carried out,
overload 1 (alarm 50) will occur. If the maximum current is commanded at 95% or higher continuously
for one second or more due to a machine collision, etc., overload 2 (alarm 51) will occur.
(1) Motor
HF44
HF44 Overload protection characteristics
0.1
1
10
100
1000
10000
0
100
200
300
400
500
Current (stall %)
Ti
me (s
)
When rotating
When stopped
(2) Motor
HF74
HF74 Overload protection characteristics
0.1
1
10
100
1000
10000
0
100
200
300
400
500
Current (stall %)
Ti
me (s
)
When rotating
When stopped
