TechTips

Categories

CA7 Contactors

RELATED LINKS

Literature

Technical Tips & FAQs

Basics For Selecting A Motor Starter

The use of the term ‘motor starter’ implies that there are two components –

  1. Controller (Contactor)
  2. Overload Relay

Controller + Overload Relay = Motor Starter


Making the correct selection of the motor starter is indicative of knowing the following characteristics:

Type of Motor Starter

  1. Manual Starter
    actuation is done manually by turning a knob on a device possessing an integral overload (i.e.; Sprecher+Schuh KTA5/KTA7 series)
  2. Magnetic Starter
    actuation is done with an electrical signal sent to the coil of a contactor (i.e.; contactor + overload)

Contactor Size and Line Power

How much current needs to flow through the power contacts of L1-T1/L2-T2/L3-T3? What line voltage is being used for the supply of power? 1Ř? – or, 3Ř?
Reference is to be made with the motor nameplate to identify the line voltage and horsepower (HP) necessary for the rating approval. The contactor selection will have a higher current (amp) rating than the FLA of the motor at the line voltage intended.

For this comparison – there are two types of contactors:

  1. UL/HP rated 
    (i.e.; Sprecher+Schuh CA7/CA8/CA9 series)
  2. NEMA rated
    (i.e.; Sprecher+Schuh CAN7 series)

Overload Relay Range

What is the FLA (Full Load Amps) of the motor load?
Dependent on the contactor selection – the overload relay is compatible for direct-connection to the contactor and the choice will possess the FLA within its given amp range. There is no calculation necessary by the user and the FLA from the motor nameplate data is intended to be dialed into the factory calibrated device. Option(s) for overload relays:

Solid State Overload Relays Thermal Bimetallic Overload Relays

Control power - Contactor Coil

What is the voltage of the coil to be inside the contactor?
The coil voltage selection of the contactor is aligned with the control circuit voltage. This is the control power used to energize/de-energize (close/open) the contactor.

Getting beyond the basics

The simplicity of providing a controller/contactor and overload in component form is catagorized as being 'Open Type'. There are other Discovery Questions that increase the acumen of getting down to the specifics of the starter requirements.



Manual Starter

KTA5
KTA5
KTA7
KTA7


Magnetic Starter

combination starter type
Motor Controller
CEP7-1
Overload
Magnetic Starter
Magnetic Starter


Combination Starter

Two Component Type E Combo

combination starter type
Motor Controller
combination starter type
Contactor
Combination Controller

Three Component Type E Combo

combination starter type
Motor Controller
combination starter type
Contactor
Overload
Combination Controller


Classic Combination Starter

CA7-37 Contactor
Molded Case Curcuit Breaker +
Contactor + Overload = Combination Starter

Jason McCoy

Jason McCoy, Product Manager

Contact me via email

Connected on LinkedIn

Request more Info