Guidelines

How do you select a contactor for a 3 phase motor?

by Author

How do you select a contactor for a 3 phase motor?

When selecting a contactor, please make sure that the contactor’s rated current is specified for the AC-3 load type. Ensure that you are looking at the right table. You can see the rated current for the AC-3 load is lower than the rated current for the AC-1 load.

What type of contactor would be used on a three-phase motor?

For the control of three-phase motors, magnetic contactors are used to open and close the power contacts in line with the motor.

How do you know which contactor to use?

Power contactors have 3 poles or 4 poles versions. You should select the suitable contactor according to the number of phases of the load. For example, if you want to control a 3 phase motor, you should use 3 pole contactor. If you want to disconnect the neutral, your choice should be 4 pole version.

READ ALSO:   Does list allow null?

How do you size a 3 phase contactor?

As per above chart:

  1. Type of Contactor = AC7b.
  2. Size of Main Contactor = 100\%X Full Load Current (Line).
  3. Size of Main Contactor = 100\%x6 = 6 Amp.
  4. Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line).
  5. Making/Breaking Capacity of Contactor = 8×6 = 52 Amp.

Can a three phase contactor be used for starting a single phase motor?

Single phase power is typically reserved for lower power requirements, however in some cases powering a small motor with single phase input power is practical.

What is AC2 contactor?

AC-2: These are used in slip-ring motors starters such as Switching on and switching off the motor. AC-3: These types of contactors are generally preferred for the starting of Squirrel-cage motors, and switches off motor during the running time which means the contactor can withstand high current continuously. Example.

What are the types of contactors?

There are different types of contacts in a contactor, and they are; auxiliary contact, power contact, and contact spring. The power contact has two types that are; stationary and movable contact. Material for making contacts must have a high welding resistance and stable arc resistance.

READ ALSO:   Does jazz come from classical music?

Can you oversize a contactor?

A contactor is a glorified switch and the ratings are for its own function. You want to avoid under-sizing a contactor, but you can oversize.