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 causes a contactor to fail?
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.
How does a magnetic contactor work?
Function. When electricity flows through the magnetic contactor, it causes the electromagnet to generate a strong magnetic field. This field pulls the iron core into the coil, and creates an electrical arc. Electricity passes in through one contact and into the contactor’s parent device in this manner.
How many ohms Should a coil read?
Most ignition coils should have a primary resistance falling somewhere between 0.4 and 2 ohms; however, refer to your manufacturer’s specifications for the correct reading. If a reading of zero is displayed, that signifies that the ignition coil has shorted internally in the primary windings and needs to be replaced.
How many ohms should a contactor coil have?
Touch each lead to the coils connectors like reading the voltage, but with the meter in the ohms position. The meter should read from 10 to 100 ohms. If the meter does not, the coil is bad and must be replaced.
Can you bypass a contactor?
A 2-contactor bypass allows a technician to flip the switch, bypass the VFD, and the motor will resume running at 100 percent speed. Eventually, the systems should be shut down in order to safely replace the drive.
When should a contactor be replaced?
Your contactor can fail electrically in one of three ways. The coil can become shorted, grounded, or open. Your technician will use a meter to determine the resistance crossing your contactor. If the readings are outside of a very narrow range; your contactor should be replaced.
How long do contactors last?
Why do contactor coil burn out?
Reason for coil burns: Coil may burn when the voltage applied to the contactor coil ends is lower or higher than normal. In addition, dust and foreign bodies in the air gap facilitate this.
How contactor is connected?
A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 230-volt motor switch. Unlike general-purpose relays, contactors are designed to be directly connected to high-current load devices.
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.
Why magnetic contactor is used?
Magnetic contactors are used in the electric motors to balance the change in frequency of the motor or the state of the motor which can be termed as the switching of the motor from ON and OFF state. … Magnetic contactors act as a safeguard to protect the power supply and the motor.