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A defrost control typically.

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Q: What is the purpose of a timer wired into the compressor contactor control circuit on a refrigeration system?
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How many wires to control a mechanically held contactor?

A contactor is a type of switch. However this switch uses electricity to power an electromagnetic coil to switch on or off power. Hence a contactor needs 2 wires - A live/hot wire and a neutral wire. Generally these are connected across the A1 and A2 terminals of the contactor.


What is the function of contactor?

A contactor is used like a switch. It is used to open and close the circuit it is in series with by electrically energizing and de-energizing the holding coil of the contactor. By having this adaptability the circuit can be remotely operated from a distance and the operator does not have to be in close proximity to the circuit. Contactors are used to remotely operate banks of lighting and of course the contactor is used for motor control. On contactors that control motors an additional overload block is added to the bottom side of the contactor to protect the motors if they get into an over load condition. The N.C. contacts in the overload block will open and the holding coil of the contactor will de-energize and drop the motor off line.


Can a 3 phase contactor be wired for single phase?

Yes, L1 of the single phase supply is terminated under terminal L1 of the three phase contactor. L2 of the single phase supply is terminated under terminal L2 of the three phase contactor. A conductor from output terminal T2 is then taken to input terminal L3. The single phase load is then connected to the contactor's output terminals T1 and T3. This incorporates all three of the overload blocks on the contactor into the control circuit. With the overloads in the control circuit, if an overload occurs the magnetic contactor's holding coil will drop out and take the load off line.


What usually cause the star contactor to burn on a star delta starter?

A lot of designers will fit an under rated star contactor, partly for cost saving purposes and partly down to the fact that the star contactor will only stay energised for a brief period. Burning out the star contactor could be down to it staying in circuit too long, not changing over to delta, a timer malfunction holding in the star contactor or switch that is defective in the control circuit. Another cause could be your motor is drawing excess current.


How do you wire up a 208v single phase motor with micro switch?

if you are using the pressure switch to control a 3phase pump chances are it already has a magnetic starter and a single pole control circuit i have seen small 3phase air compressors with the contacts driven right off the diaphragm bigger ones usually have 110 volt controls i would be concerned about the current rating of the switch if you are trying to switch the motor directly there are many single phase compressors that run directly from the pressure switch

Related questions

What device is the only load in the control circuit of a condensing unit?

I think that would have to be some relay or contactor coil for a fan, compressor or relay contacts.


Why is the compressor contactor not sticking in?

A contactor not being energized or closed can be caused by a host of reasons . A shorted or open contactor coil. No control voltage or incorrect voltage present to energize the contactor coil , A safety device opening or breaking the control circuit . A loose or broken control devise or control wire . and possibly more , depending on your a/c units control wiring configuration. Tom H, HVAC proffesional. New Orleans .


How does magnetic contactor operate?

explain me about the contactor works with examples. if i want to control a motor with contactor. and how i can use contactor in loops with over load and circuit breakers.


How many switches can be connected to a contactor coil control circuit?

unlimited


How many wires to control a mechanically held contactor?

A contactor is a type of switch. However this switch uses electricity to power an electromagnetic coil to switch on or off power. Hence a contactor needs 2 wires - A live/hot wire and a neutral wire. Generally these are connected across the A1 and A2 terminals of the contactor.


What is the function of contactor?

A contactor is used like a switch. It is used to open and close the circuit it is in series with by electrically energizing and de-energizing the holding coil of the contactor. By having this adaptability the circuit can be remotely operated from a distance and the operator does not have to be in close proximity to the circuit. Contactors are used to remotely operate banks of lighting and of course the contactor is used for motor control. On contactors that control motors an additional overload block is added to the bottom side of the contactor to protect the motors if they get into an over load condition. The N.C. contacts in the overload block will open and the holding coil of the contactor will de-energize and drop the motor off line.


What is the function of the current sensing relay in an oil safety control scheme?

The electrical control panel for a refrigeration unit using single or three phase power. The control portion has an oil pressure safety switch, defrost timer, temperature controls and perhaps a refrigerant pressure control in conjunction with the normal internal overload circuit breakers for the compressor. After operation of the refrigeration unit for a period of time, a defrost control device cuts off the compressor and turns on the electric defrost heaters. As the evaporator coils are defrosted, defrost thermostats open the defrost heater supply circuits. When the current sensing relay senses that all the defrost heaters have been shut off via the defrost thermostats, a time delay relay will return the refrigeration unit to the normal refrigeration cycle. The same current sensing relay will prevent false triggering by the oil pressure safety switch if the compressor's internal overload circuit breaker opens


On a heat pump the outside fan is not running when it's in ac mode contactor not pulled in why?

No control power to the contactor coil. You must trace the control circuit back until you find the open switch that is interrupting the flow of power and correct the problem.


How do electro pneumatic contactors work?

A contactor is an electrically controlled switch (relay) used for switching a power circuit. an electro pneumatic contactor is similar to the above except it uses a pneumatic signal to initiate the switching of the electric power circuit. an electro magnetic contactor is a contactor driven by an electric control signal. It us usually just called a contactor.


Can a 3 phase contactor be wired for single phase?

Yes, L1 of the single phase supply is terminated under terminal L1 of the three phase contactor. L2 of the single phase supply is terminated under terminal L2 of the three phase contactor. A conductor from output terminal T2 is then taken to input terminal L3. The single phase load is then connected to the contactor's output terminals T1 and T3. This incorporates all three of the overload blocks on the contactor into the control circuit. With the overloads in the control circuit, if an overload occurs the magnetic contactor's holding coil will drop out and take the load off line.


What usually cause the star contactor to burn on a star delta starter?

A lot of designers will fit an under rated star contactor, partly for cost saving purposes and partly down to the fact that the star contactor will only stay energised for a brief period. Burning out the star contactor could be down to it staying in circuit too long, not changing over to delta, a timer malfunction holding in the star contactor or switch that is defective in the control circuit. Another cause could be your motor is drawing excess current.


How do you wire up a 208v single phase motor with micro switch?

if you are using the pressure switch to control a 3phase pump chances are it already has a magnetic starter and a single pole control circuit i have seen small 3phase air compressors with the contacts driven right off the diaphragm bigger ones usually have 110 volt controls i would be concerned about the current rating of the switch if you are trying to switch the motor directly there are many single phase compressors that run directly from the pressure switch