How do you connect an overload relay?
Connection of Overload Relay with Contactor Insert the metallic rod terminals of the overload relay to the bottom side of the contactor as shown in the above figure, then tighten the screws. Now the overload relay properly connected with the contactor.
What are the parts of a thermal overload relay?
A melting alloy (or eutectic) overload relay consists of a heater coil, a eutectic alloy, and a mechanical mechanism for breaking the circuit. Using the heater coil, the relay measures the motor’s temperature by monitoring the amount of current drawn.
How does a thermal overload relay work?
A thermal overload relay works in the principle of electro-thermal properties in a bimetallic strip. When the bimetallic strips heat up, the trip contact is activated that in turn breaks the power supply to the contactor coil, de-energizing it and breaking the current flow to the motor.
How do you set a thermal overload relay?
Thermal Overload Relay setting = 100% x Full Load Current (Line).
- Thermal Overload Relay setting = 100% x Full Load Current (Line).
- Thermal Overload Relay setting = 100%x6 = 6 Amp.
What are the three types of overload relays?
A few different types of overload relays include Bimetal Overloads, Ambient-Compensated Overload Relay, and Electronic Overload Relays. Bimetal Overloads use a bimetal strip that acts as a trip lever. When there is an overload condition, the bimetal strip becomes heated and will bend to close and trip the circuit.
What is 95 and 96 on a contactor?
The contact 95-96 is used to control the load contactor. The overload relays have a setting scale in Amperes, which allows the direct adjusting of the relay without any additional calculation.
What are 2 types of overload relays?
How do you test a thermal overload relay?
Overload Protection Test:
- Measure the normal motor running current (i motor).
- Turn off the motor and let it cool for about 10 minutes.
- Calculate the following ratio: i (motor) / i (overload min FLA).
- Set the overload to its minimum FLA and turn on the motor.
- Wait for the overload to trip.
What should A thermal overload be set to?
2) Thermal Overload Set Incorrectly-The basic requirement for overload protection setting for motors is 125% of their full-load current according to the NEC; however, it makes sure you read the overload relay instructions.
What are thermal relays?
Thermal relays are protective electrical appliances used for overload protection of motors or other electrical equipment and electrical circuits. If the overload current is small and the overload time is short, and the motor winding does not exceed the allowable temperature rise, the overload is allowed.
How do you troubleshoot a thermal overload relay?
Unplug your appliance from its power supply before attempting to test its thermal overload switch. Make sure to disconnect the supply of gas from gas appliances.
Connection for mounting onto contactors
What does thermal overload relay means?
Thermal overload relays are protective devices. They are designed to cut power if the motor draws too much current for an extended period of time. To accomplish this, thermal overload relays contain a normally closed (NC) relay.
What is the function of an overload relay?
Allow harmless temporary overloads (such as motor starting) without disrupting the circuit.