Magnetic contactors are a form of electrical relay found on most electrically powered motors. They act as a go-between for direct power sources, and high-load electrical motors in order to homogenize or balance out changes in electrical frequency which may come from a power supply as well as to act as a safeguard.
What is the main function of contactor?
Function of contactor, generally used for connected and disconnected of electric current supply. Usually in use for applications: motors, heater, lighting or electric power distribution.
What is the main difference between a relay and a 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.
What are the parts of magnetic contactor?
A contactor has three components. The contacts are the current-carrying part of the contactor. This includes power contacts, auxiliary contacts, and contact springs. The electromagnet (or “coil”) provides the driving force to close the contacts.
How do you test a magnetic contactor?
Turn the control switch on to energize the coil in the contactor. You should hear a clear clicking and humming sound. Other magnetic contactors have a visual hint once the coil is energized. Get the volt ohmmeter and turn it on.
What is NO and NC In Contactor?
Relays and contactors have two types of contacts, each suited for different applications: Normally open (NO) contacts allow current when the relay or contactor is energized. … Normally closed (NC) contacts allow current through when the relay or contactor is not energized.
What is the criteria to select the contactor?
In order to correctly select a contactor for your application, you will first need to consider the following points. Control circuit voltage e.g. 24VAC, 230VAC, 400VAC, 24VDC etc. Note: If AC then select correct supply frequency, if DC is low power consumption option needed?3 мая 2017 г.
What is the purpose of contactor or relay?
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.
What is the main function of overload relay?
Overload relays cut off current to the motor when a high-current situation develops due to a ground fault, short circuit, phase failure, or mechanical jamming. They are an inexpensive way of avoiding downtime for repair or replacement of failed motors from excessive current.
What causes contactor failure?
Electrical failure – Three different electrical issues can cause contactor failure. The insulation between the coil wires can break down and cause a short. The coil can become grounded through another metal component when the wiring insulation deteriorates. The coil can also become stuck in an open position.
What is contactor and types?
A contactor is an electrical device which is used for switching an electrical circuit on or off. … Contactors are most commonly used for controlling electric motors. There are various types of contactors, and each type has its own set of features, capabilities, and applications.
How does contactor work PDF?
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 relay do?
What Is a Relay? Relays are electric switches that use electromagnetism to convert small electrical stimuli into larger currents. These conversions occur when electrical inputs activate electromagnets to either form or break existing circuits.
How do I know if my contactor is bad?
These bad AC contactor signs may include:
- Humming. When your AC is on, it may produce a humming sound – but, it won’t power on. …
- Chattering. When the contacts are dirty, or the coil has become weak, you may hear the plunger make a chattering sound. …