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Glossary

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  • A

    • Actuator
      The assembly portion of the contactor or relay that converts electrical energy into mechanical work. This includes the coil assembly, magnetic frame, and pole pieces.
    • Ampere-Turns
      The product of the number of turns of a coil winding and the current passing through the coil windings at any given voltage.
    • Armature
      The moving magnetic member of an actuator assembly. Also known as plunger or moveable core.
    • Auxiliary Contacts
      An additional set of contacts added to a contactor that is used for low-level circuitry. Usually in the form of a snap action microswitch. Multiple configurations are available.

  • B

    • Bobbin
      A spool like form, made from insulating material, used to hold the coil windings.
    • Bounce, Contact
      The intermittently momentarily opening of closed contacts or closing of open contacts.
    • Bracket
      A formed piece of sheet metal attached to a contactor for mounting. Multiple configurations are available.
    • Break, Contact
      The opening of closed contacts to interrupt an electric circuit.

  • C

    • Change Over Contactor
      A contactor with a set of normally open and normally closed contacts. Also known as a double throw contactor.
    • Coil
      An assembly consisting of one or more windings of insulated magnet wire wound on a bobbin. Used to generate the flux in the magnetic circuit of the actuator. Can have UL insulation class rating (AMETEK standard is Class H, 180°C).
    • Coil, Economized
      A coil that utilizes high current to close the contacts and then switches to a lower current to keep the contact closed. The switching can be done electronically or by the use of a microswitch.
    • Coil, Suppressed
      A coil with electronic components used to limit the self-induced coil voltage when the coil is de-energized. This is helpful in protecting sensitive equipment. Various electronic components are available (i.e. varistor, zener diode, resistor, etc.). The component used will have an effect on the release time of the contactor.
    • Conductor
      A material that permits a generous flow of electrons.
    • Contactor, Latching
      A contactor that maintains its position after power has been removed from the coil. Typically, the contacts are held closed through the use of a permanent magnet, and held open through the use of a spring. To close the contacts, a short pulse is applied to the coil. To open the contacts, a short pulse of opposite polarity is applied to the coil. The duration of the pulse can be found on the data sheet.
    • Contacts
      The current carrying parts of a contactor that open or close an electric circuit. Can be made from various materials depending on current levels, Silver Tin Oxide being the most common for high current applications. Also known as Tips.
    • Contacts, Serrated
      Contacts with a textured surface. Useful in the beginning of the life of the contacts by the creation of multiple points.
    • Core, Moveable
      See armature.
    • Current, Inrush
      A temporary large current developed from a motor when it is initially started.

  • D

    • Dielectric Strength
      The maximum allowed voltage between two specified points. The voltage is usually specified in AC rms, 50/60 Hz, but can also be specified in DC.
    • Diode
      An electrical component that allows current to flow in only one direction.
    • Duty Cycle
      A term used to explain the operation of a coil that is based on heating factors. Usually expressed as a percentage. Defined as the “on” time divided by the sum of the “on” time and “off” time.

  • E

    • Electromagnet
      A device consisting of a soft iron or steel core surrounded by a coil.

  • F

    • Force, Contact
      The force exerted on the moveable and stationary contacts when closed.
    • Frame
      The magnetic steel members that surround the coil in the actuator assembly and complete the magnetic circuit. The frame can also act as the main supporting member of the contactor.

  • G

    • Gap, Contact
      The distance between a pair of mating contacts when they are in the open position.

  • I

    • Inductor
      See “coil”
    • Insulator
      A material that resist the flow of charge. It is understood to have a high electrical resistance.

  • L

    • Load, Contact
      The electrical power the contacts are intended to switch in any particular application. There are two major types:
      1. Resistive Load: The load is created from the resistance in the circuit.
      2. Inductive Load: The load is created from the inductance in the circuit.
      2.1 Motor Load: Same as an inductive load, but with a high inrush current. AMETEK typically has multiple ratings.

  • M

    • Magnets, Blowout
      A fixed set of magnets aligned with a pair of mating contacts that assist in quenching the arc in high voltage applications during opening of the contacts. The addition of blowout magnets to a contactor causes it to be polarity sensitive. Care must be taken to correctly attach the contactor in a circuit. Typically, blowout magnets are standard in the following applications.
      • Resistive Loads >60 Volts
      • Inductive Loads >48 Volts
    • Make, Contact
      The closure of open contacts to complete an electrical circuit.

  • O

    • Overtravel, Contact
      The distance the moveable core travels after open contacts touch.

  • P

    • Power
      The indication of how much work can be accomplished in a specified amount of time. The electrical unit of measure is the Watt (W).