HOW DO I WIRE A SINGLE PHASE MOTOR THROUGH A 3-PHASE CONTACTOR?

A Quick Introduction:

Single phase power can be replaced by a three phase motor starter. The rewiring is not too technical and the three phase motor starter proves to be more economical in usage. Overload relays come into play here and just to jog our memories; overload relays are just magnetic motor starters.

Now, overload relays are set in such a way that any current directed to the motor is passed between the phases. If one phase is rewired, one of the contacts will take in all the current and by this we have an overloading situation. There are ways to prevent this of course and one of these ways will be outlined below. This method will show us how to balance the current by rewiring the starter on the overload relay.

3-Phase Contactor: The Process

Although there is no diagram available, the 3-phase contactor can be described to the latter. The three phase contactor has four terminals for three pole and an auxiliary contact. The contactor itself is at the top and the overload relay is attached to the bottom. it is to be noted that the auxiliary contacts can be utilised as a sort of switch for a pilot light on a control panel.

Things you’ll need handy:

  • Jumper wire
  • 2 power leads
  • Wire gauge (the wire gauge should be selected based in the current passing through the contactor)

Directions

  • Bring the two power leads together on the contactor (L1 and L2).
  • On the overload relay, connect the jumper wire (L3) on the contactor to Terninal 2 (i.e. T2)
  • Connect the leads to Terminals 1 and 3 (T1 and T3).

This method is short and to the point but there are others. By this, the current is well balanced all the poles on the relay.

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