How does a DC contactor work?
The Basics of DC Contactors The contactor functions by applying a voltage to the coil, this creates a magnetic field which moves the contacts to the closed position and completes the circuit. Once voltage is removed from the coil, the contacts will open back up and disconnect the circuit.
Why AC contactors Cannot be used for dc applications?
The inductance of the inductor is proportional to the frequency. So AC contactors and DC contactors cannot be replaceable to each other. If we put the AC contactor in the DC circuit, it will burn out because of the excessive current. Because there is inductive reactance in alternating current but not in direct current.
Where are contactors 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.
Is a contactor a 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 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 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 is NO and NC In Contactor?
NO (Normally Open) is When a Magnetic Contactor has not been given an Electric voltage (Normal state), then this Pole is not connected (Open), then when the Coil on the magnetic contactor is given a voltage then this Pole will be connected (closed). NC (Normally Close)
What is the difference between a current and potential relay?
Potential relays (relays are used, as a rule, high-torque capacitor-start the engines. They slightly resemble the current relay. However, these relay is based on the increase in voltage. The increase comes as a device approaches and reaches its rated speed.
What is the purpose of the starting relay?
One of the most important – and most forgotten – components of any vehicle’s ignition system is the starter relay. This electrical part is designed to redirect power from the battery to the starter solenoid, which then activates the starter to spin over the engine.
What does a current relay do?
A current relay is a type of electromagnetic switch used as part of the control systems for electrical equipment. These relays are commonly used as sensors (current sensor/monitoring relays) to monitor current flow within industrial and other safety-sensitive equipment.
What is a potential relay?
Potential or “voltage” relays are used with single-phase capacitor-start/capacitor-run motors, which need relatively high starting torque. Their main function is to assist in starting the motor. Potential starting relays consist of a high resistance coil and a set of normally closed contacts.
What are 3 types of start relays?
Several types of starting relays are used to assist in the starting of single-phase compressors. These include the current relay, potential relay, and PTC (positive temperature coefficient) relay. Each performs the same function but in a different manner.
What happens when a potential relay fails?
If the contacts of the relay are stuck open, the starting components will not be in the circuit during the starting of the motor and the motor will not have sufficient torque to start, and again the compressor will cycle off on its overload.
How do potential relays work?
A potential relay senses voltage across the start winding. When this voltage reaches a sufficient level, the start capacitor, which is in series with the start winding, must be disconnected from the circuit. This voltage is a function of the speed of the motor and the number of turns in the start winding.