Operating modes of the motor
Operating modes S1 ... S10 as specified by EN 60034-1 describe the basic stress of an electrical
machine.
In continuous operation a motor reaches its permissible temperature limit if it outputs the
rated power dimensioned for continuous operation. However, if the motor is only subjected to
load for a short time, the power output by the motor may be greater without the motor
reaching its permissible temperature limit. This behaviour is referred to as overload capacity.
Depending on the duration of the load and the resulting temperature rise, the required motor
can be selected reduced by the overload capacity.
The most important operating modes
Continuous operation S1
Short-time operation S2
P
P
V
t
t
t
J
P
P
V
t
t
t
J
t
B
Operation with a constant load until the motor reaches the thermal
steady state. The motor may be actuated continuously with its rated
power.
Operation with constant load; however, the motor does not reach the
thermal steady state. During the following standstill, the motor winding
cools down to the ambient temperature again. The increase in power
depends on the load duration.
Intermittent operation S3
Non-intermittent periodic operation S6
P
P
V
t
t
t
J
t
S
t
L
t
B
P
P
V
t
t
t
J
t
S
t
L
t
B
Sequence of identical duty cycles comprising operation with a constant
load and subsequent standstill. Start-up and braking processes do not
have an impact on the winding temperature. The steady-state is not
reached. The guide values apply to a cycle duration of 10 minutes. The
power increase depends on the cycle duration and on the load period/
downtime ratio.
Sequence of identical duty cycles comprising operation with a constant
load and subsequent no-load operation. The motor cools down during
the no-load phase. Start-up and braking processes do not have an
impact on the winding temperature. The steady-state is not reached. The
guide values apply to a cycle duration of 10 minutes. The power increase
depends on the cycle duration and on the load period/idle time ratio.
P
Power
P
V
Power loss
t
Time
t
B
Load period
t
L
Idle time
t
S
Cycle duration
ϑ
Temperature
Appendix
Good to know
Operating modes of the motor
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