Answer / navnit bhimani

Motor full load current=H.P.x1.5 in three phase line
Motor full load current=H.P.x4 in single phase line
you can select 20% over size than full load current.

Answer / prabhu gnanasekaran

All power contactors has to be selected as per the TYPE 2
CO-ORDINATION chart. Which will have the KW rating of the
motor with Line current and starting current. So TYPE 2 CO-
ORDINATION chart will be the base for the selection of
power contactors.

Answer / sahilsmohan

This is depend of utilization of motor :
A.C motor) A.C 1 to A.C 4 : slightly
inductive,slipring,squirel cage ,starting ,stoping, and
plugging, inching .

DC motor ) DC1 TO DC4 slightly induction, series
/shunt,staring stopping, pluging, inching

Answer / amit kansara

first of all determine what is the duty type - ac-2/ac-3 /ac-4
accordingly select the right contactor for manufacturers
catalogue.

Answer / pvr.parthasarathi

For selecting a power contactor for a particular motor the following points are to be considered.
1) Type of the motor ie. Squirrel cage, Slipring .
2) Full load of the motor and its Voltage .
3) Operating cycle of the motor ie. S1 , S2 -----.
4) Nature of the drive ie. cycle of operation such as normal , jogging, Breaking etc.

So selecting the contactor for a motor does not have single point formula. But as a thumb rule for 3 phase motors it can be selected at 130 percent of FLC, if all other factors are normal.

Answer / pramod

As per the different manufacture the give its selection
chart but techanically calculate the motor full load current
of the motor and select the nearst current size of contactor
as per different manufacture Power Contactor List

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