Contents
What is the contactor controlled by?
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 an electronic contactor?
A contactor is an electrical device which is used for switching an electrical circuit on or off. Generally, these electrical devices feature multiple contacts. These contacts are in most cases normally open and provide operating power to the load when the contactor coil is energized.
Can a PLC control a contactor?
The direct control of contactor coils from the PLC reduces the costs for coupler relays and reduces the wiring effort involved. For this the output must provide both the pick-up and the holding power for the contactor coils. PLC’s with differ- ent outputs are available on the market.
How do you test for a magnetic contactor repair?
To test a contactor with a multimeter or voltmeter, use the following steps as a guide.
- Remove wires from the line.
- Remove wires from the terminal.
- Turn on the control switch.
- Connect the multimeter.
- Test each line.
- Check for a faulty coil connection.
- Check voltage.
- Check ohms.
How does a PLC execute a program?
Execute Program (or Logic Execution): The PLC executes a program one instruction at a time using only the memory copy of the inputs the ladder logic program. For example, the program has the first input as ON.
What are coils in PLC?
Contacts and coils are discrete programming elements, dealing with Boolean (1 and 0; on and off; true and false) variable states. Each contact in a Ladder Diagram PLC program represents the reading of a single bit in memory, while each coil represents the writing of a single bit in memory.
Can a contactor be used in a control circuit?
The coil voltage of a contactor or relay can be installed for virtually any control circuit voltage, to provide complete flexibility for these devices (both AC and DC), as the control circuit can be completely independent of the load it is switching.
Contactors and relays are operated by applying a voltage to the coil of an Electro-magnet, which will cause a switch, (or several switches) to close. The circuit that applies the voltage to the coil is referred to as the control circuit, because it controls the main device that the contactor or relay is switching.
How are universal coils used in a contactor?
The universal coils are the ones that can operate on AC as well as DC voltages. A small amount of power is drained by the coil during the switching operations. Economiser circuits are used to reduce the power consumed by the contactor during its operation. Contactors with AC coils have shading coils.
Where are the main contacts located in a contactor?
A spring which is located between coil and the movable core, auxiliary contacts it could be normally open or closed. The main contacts cut on and off the light current loads such as contactors coil, relays, timers, and many other control circuit parts are linked to contact mechanism.