Operating Principle of a Contactor:The current passing through the contactor excites the electromagnet. The excited electromagnet produces a magnetic field, causing the contactor core to move the armature. A normally closed (NC) contact completes the circuit between the fixed contacts and the moving contacts.
What is a motor contactor?
A contactor is a large relay, usually used to switch current to an electric motor or another high-power load. Large electric motors can be protected from overcurrent damage through the use of overload heaters and overload contacts.
Why contactor is used in motor?
A contactor is an electrically-controlled switch used for switching an electrical power circuit. … Unlike relays, contactors are designed with features to control and suppress the arc produced when interrupting heavy motor currents.
Are contactor contacts wired like a load or a switch?
A contactor is really just a bigger relay. The key to understanding relay operation is realizing that a relay is actually two electrical devices: a set of contacts and a coil. The contacts are a switch. They are wired in circuits exactly like switches and they behave like switches because they are switches.
What is the main function of contactor?
A contactor is a special type of relay used for switching an electrical circuit on or off. They are most commonly used with electric motors and lighting applications.
What are the three parts of a contactor?
A contactor consists of three basic parts: the operating coil, the associated magnetic circuit and the contacts that are actuated by the coil.
Does a motor need a contactor?
the requirement to switch large currents both on and off require a contactor. this prevents welding the contacts on start and breaks the arc associated with opening the contacts. in special cases, it may be necessary to have magnetic blowouts to prevent the arcing when the contacts open.
What is NO and NC In Contactor?
NO (Normally Open) is When a Magnetic Contactor has not been given an Electric voltage (Normal state), then this Pole is not connected (Open), then when the Coil on the magnetic contactor is given a voltage then this Pole will be connected (closed). NC (Normally Close)
What is difference between relay and contactor?
A contactor joins 2 poles together, without a common circuit between them, while a relay has a common contact that connects to a neutral position. Additionally, contactors are commonly rated for up to 1000V, while relays are usually rated to only 250V.
Why use a contactor instead of a switch?
Contactors are used for high power applications. They allow a lower voltage and current to switch a much higher power circuit, so they are generally larger and more heavy-duty than control relays, enabling them to switch higher power loads on and off for many thousands of cycles (Figure 1).
What are the two basic 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.
How do you wire a 3 phase contactor?
How to Wire a Three-Phase Contactor
- Shut off the power to the three-phase load. …
- Take additional black, red, and blue three-phase wire that is the same size as the supply wires and connect one end of these wires to the T1, T2, and T3 terminals on the contactor. …
- Connect the control circuit to the positive and negative control terminals of the contactor.
Does a contactor need a neutral?
In general, no, a it is not necessary that a lighting circuit, of which a contactor is a part, have a neutral conductor in all cases. The contactor must open all UN-grounded conductors. If the contactor is a single pole, then one of the current carrying conductors must be a groundED (not the groundING) conductor.
Is A2 neutral on a contactor?
When the photcell switches on , the contactor coil will energise and open the contacts. Any contact with a 1 & 2 are N/C and 3 & 4 are N/O, A1 is the live and A2 the neutral.