What is a potential relay do?
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 the three potential relay rating voltages?
The potential relay is rated by, and operates on, three voltage ratings: pickup voltage—the minimum voltage required to energize the coil and open the NC contacts; dropout voltage—the minimum voltage the coil requires once it’s energized to keep the contacts from closing; and continuous coil voltage—the maximum voltage …
How do you troubleshoot a potential relay?
A simple ohmmeter is all that is needed to troubleshoot a potential relay. After taking all of the connecting wires off of the potential relay, measure the resistance across the 1 and 2 terminals. The resistance should read close to zero, since there are normally closed contacts between terminals 1 and 2.
How is a potential relay energized?
The potential relay consists of a very high-resistance coil and a set of normally closed contacts. When power is delivered to a single-phase motor, both the run and start windings will be energized because the contacts between terminals 1 and 2 of the potential relay are normally closed.
Is a relay the same as a capacitor?
You will often see capacitors placed across the coil contacts of a relay. A capacitor takes some time to charge up, so it can be used to make a time delay relay. Warning: A capacitor and a relay coil (which is basically an inductor) are both energy storage devices.
Is a potential relay position sensitive?
Yes, potential relays are position sensitive. Each must be calibrated for the position it’s to be used in. By installing one in an incorrect position, you risk, altering the Pick up and Drop out voltages.
How do you check a potential relay?
Disconnect the voltage source from the circuit and remove the relay from the circuit. First check the relay’s coil by placing the leads of the ohmmeter across the 2 and 5 terminals of the relay. If the ohmmeter reads a high resistance (approximately 3,000 to 18,000 ohms) the coil of the relay is electrically OK.
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.
Is a potential relay normally open or closed?
Potential relays are normally closed devices. This means that the relay contacts between “1” and “2” are closed when a motor is first energized. The opening of these contacts is the primary function of a potential relay.
What are three 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.