2 Engineering
2.5 Motor and Application
42 DC1 Frequency Inverter 10/12 MN04020003Z-EN www.eaton.com
2.5.5 Bypass operation
When it is necessary to be able to power the motor directly with mains volt-
age independently from the frequency inverter (bypass operation), the
branches must be mechanically interlocked.
Figure 16: Bypass motor control (example)
NOTICE
The system may only switch (S1) between the frequency
inverter (T1) and mains voltage (see Figure 16) while in a
de-energized state.
CAUTION
The frequency inverter’s outputs (U, V, W) must not be con-
nected to the mains voltage (destruction risk, fire hazard).
￫
When running the motor directly with mains voltage, protective
measures (circuit-breaker with thermal overload protection or
overload relay ) against overload must be in place.
￫
Contactors and switches (S1) in the frequency inverter output
and for the direct start must be designed based on utilization
category AC-3 for the rated operational current of the motor.
Q1
I
>
I
>
I
>
Q11
S1
M1
T1
M
3h
L1
L2
L3
L1 L2 L3
UVW
a
b
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