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Electrically held contactors - Siemens contactor type CLM
Electrically held contactors - Siemens contactor type CLM

Most lighting and heating applications require a contactor to control the loads. One type of contactor is an electrically held contactor, which is similar to a magnetic starter. Unlike a magnetic starter, however, a lighting and heating contactor is designed for lighting and resistive heating loads rather than motor loads.

Siemens class LE lighting and heating contactors are available with 2 to 12 poles rated from 20 to 400 amps.

They can be used on 480 VAC tungsten and 600 VAC ballast-type lighting loads as well as 600 VAC resistive loads. Enclosures are also available.

Electrically held lighting contactors are similar to the magnetic contactors and starters discussed previously. When current is applied to the coil, all normally open contacts close. If power is lost, these contacts open, removing the supply of current to connected loads.

Because the constant current flow needed to keep the contactor energized causes a humming noise, these contactors should not be used for applications such as libraries, hospitals, and some commercial buildings where this noise will be a problem.

The following diagram shows a typical on/off control circuit for an electrically held lighting/heating contactor.

Electrically Held Contactors - Diagram

SOURCE: Siemens – Basics of control components

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Edvard Csanyi

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV high power busbar trunking (<6300A) in power substations, buildings and industry fascilities. Designing of LV/MV switchgears.Professional in AutoCAD programming and web-design.Present on

4 Comments


  1. Scholtzf1
    Oct 03, 2013

    A very useful control circuit know to technicians as a “holding circuit”. Also acts as a safety device in case the mains fail to prevent the unexpected startup of machinery when mains return.

  2. […] switch a large amount of electrical power through its contacts, it is designated by a special name: contactor. Contactors typically have multiple contacts, and those contacts are usually (but not always) […]


  3. slavisa
    Feb 07, 2011

    TEST

  4. […] This post was mentioned on Twitter by Electric Engineering, Electric Engineering. Electric Engineering said: Electrically Held Contactors – Siemens http://t.co/ArNWWZx […]

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