Checklist before applying power
The MEsoftstart/I series soft starter is a highly reliable product, but an incorrect peripheral circuit may shorten the product life
or damage the product. Before starting operation, always recheck the following points:
The soft starter model is
appropriate for the motor
that will be connected to
There is adequate space
for air-flow around the soft
Terminals are insulated.
The main circuit cable
gauge is adequate.
The wiring is correct:
Wiring between the supply
(L1, L2, L3), Circuit breaker,
Fuses, soft starter and
motor is correct.
If an external bypass
contactor is used, the
wiring between the bypass
terminals is correct.
46 Precautions for use
If the soft starter model is not appropriate
for the motor that it is connected to, the
starting current may not be enough and the
motor can overheat.
- Consider a larger model soft starter.
- Consider connecting the soft starter inside
delta to the motor.
- Consider adding an external bypass
contactor (for models without built in
contactor) - this may reduce the thermal
load on the soft starter.
- Contact your local distributor for
assistance to find the best solution.
If the air-flow is restricted, the soft starter
will overheat and trip.
Use terminals with insulation sleeves to wire
the power supply and the motor.
Use an appropriate cable gauge to suppress
the voltage drop to 2% or less. If the wiring
distance is long between the soft starter and
motor, the voltage drop in the main circuit
will cause the motor torque to decrease.
Direct application of power to the motor-
side output terminals (T1, T2, T3) of the soft
starter will damage the soft starter.
Inadvertently connecting the supply lines to
the Bypass terminals will damage the soft
- Confirm that the line voltage is within the
soft starter's rated voltage range.
- Confirm that the circuit breaker selected is
adequate for the motor maximum starting
- Confirm that the fuses that are installed
are according to the specification in Table
7 for the selected soft starter model.
- Confirm that if an external bypass
contactor is used, the contactor is rated
for the operating current of the motor.
Table 4Table 4