What is contactor and relay?
Table of Contents
What is contactor and relay?
Relay – “A device by means of which contacts in one circuit are operated by a change in conditions in the same circuit or in one or more associated circuits” Contactor – “A device for repeatedly establishing and interrupting an electric circuit under normal conditions”
How do you select a motor 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.
How does overload relay work?
The overload relay is wired in series with the motor, so the current that flows to the motor when the motor is operating also flows through the overload relay. It will trip at a certain level when there is excess current flowing through it. This causes the circuit between the motor and the power source to open.
Why contactor is used?
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.
How do you select a contactor and overload relay?
Selection of contactor and overload relay for DOL starter
- Parameters to be considered during the selection.
- Calculation of full load current (FLC)
- Operational voltage and coil supply voltage.
- Type of load and duty cycle.
- Utilisation categories for contactors according to IEC/EN60947-4-1.
- Making and breaking capacity.
What is A1 and A2 on contactor?
What Do A1 and A2 Mean on a Contactor? A1 and A2 on a contactor typically refer to either end of the electromagnetic coil assembly. Most contactor manufacturers use A1 and A2 to designate the two terminals connecting electrical power to the contactor’s magnetic coil.
What causes contactor to trip?
The most common situation in contactor failures is contact sticking and coil burning. The reason for contact sticking; If more current is passed through the main power contacts than it can carry, the contacts will overheat after a while and the contacts may stick as a result of this warming.
What is A1 and A2 on a relay?
A1 and A2 on a contactor typically refer to either end of the electromagnetic coil assembly. Most contactor manufacturers use A1 and A2 to designate the two terminals connecting electrical power to the contactor’s magnetic coil.
What are the two types of relay?
Types of Relays – A Thomas Buying Guide
- Relays are electrically operated switches.
- Electromechanical relays have an electromagnetic coil and a mechanical movable contact.
- Solid-state relays are solid-state electronic components that do not have any moving components, which increases their long-term reliability.
What is the function of contactor relay?
Contactors and Control relays are electrically operated switches used for switching of loads and for controlling the electrical circuit respectively.
What is overload size?
The overloads are determined using 125% of the FLA, 7A x 1.25 = 8.75A. The maximum allowable size for the overloads is 9.8A. The overloads can be sized at 140% of the FLA if the overloads trip at rated load or will not allow the motor to start, 7A x 1.4 = 9.8A.
What is a contactor symbol?
The contactor is designated as K and, in the coil symbol, the K1/4 indicates that there are four associated contacts. Sometimes the coil designation is placed beside the coil symbol. In this case there are three normally open power contacts, and one normally open control contact.
