Contactor Coil Voltage Explained

Contactors, like circuit breakers, are used in electrical systems to control the supply of power to motors or lighting systems. A key parameter of a contactor is the coil voltage, however, the coil voltage of types of contactors on the market vary somewhat. If you are selecting a contactor for use in your application, you need to know all about contactor coil voltage so that you can select the right one for your application.
What is a Contactor
A contactor is simply a switch for use in electrical circuits for switching the supply of power to an electrical device. Found commonly in industry for systems such as motors, heating equipment, lighting or air conditioning systems and a contactor simply consists of two parts, a coil which is sensed by an external voltage, and contacts that open and close as a result of controlling the electricity flow in the circuit.
What is Contactor Coil Voltage
The voltage required on the contactor coil, in order to be energised is what is called contactor coil voltage. If the coil is energised, it then creates a magnetic field which swings the contacts either closing or opening them dependent on the way a contactor works.Coil voltages are invariably quoted as either AC or DC, and are usually derived from the supply voltage in the control circuit.
Types of Contactor Coil Voltages
There are various rating available for contactor coils and it is very important to select the correct voltage coil for your requirements.
Common Types of Contactor Coil Voltages
Here are some common voltage types for use in contactors:
AC Voltage. The majority of contactors in use in industry are of the AC coil voltage type, for example 24V, 110V, 230V, or 400V. More generally, the AC voltage is used in applications where the source of power for the control circuit from which the control is supplied is an AC voltage power source. Examples would be the general site as described above, and such other systems as commercial buildings, and larger industrial plants and facilities.
DC Voltage. In some applications, contactor coil voltages are required which are supplied from a DC voltage source. These are applications whereby the source supplying the contactor is batteries or solar panels. Common ratings of DC voltage are from 12V to 120V.
Why is the Contactor Coil Voltage Important?
The value of the coil voltage not only decides what voltage it is the coil requires, but very much governs the characteristics and suitability of the contactor.Poor choice of contactor coil voltage may have the following effects on your system:
Faulty Operation: the coil voltage must be fitted to do the job, as it were, so a coil voltage insufficient may mean the contactor not being adequately energized; while, on the other side of the coin, too high a coil voltage may also result in the coil “burning”, and perhaps the whole contactor if not protected.
Incompatibility: a contactor coil voltage must “match” with the voltage source of the control circuit voltage for proper operation.If Not, It Will Cause Malfunction.
Economy: Using the properly rated coil voltage helps to keep power drawn up to a minimum in your system.Using the right coil voltage contactor helps keep unwanted energy draw to the barest minimum.
How to Select the Correct Contactor Coil Voltage
So, what goes into selecting a contactor coil voltage? Obviously this depends on your application, but some of the things to consider are;
Voltage of the circuit to the Coil: The coil voltage should be the same as that used in the control circuit. It is wise to ask the voltage used in the control circuit before choosing a contactor.
Nature of Application: A contactor used in a low voltage application may require, say, a 24V/48V coil, whereas a bigger application may dictate a coil of the order of 110V or 230V.
Type of Power Supply: What type of Supply System powers the application? AC? or DC? Only AC coil voltage contactors are fit for powering from AC power, while battery powered/renewable energy one will require DC coil voltage contactors.
Specifications of the Contactors: All contactors come with a “data sheet” or guidelines about the recommended coil voltage ranges. Ensure you take cognizance of this in your selection of contactors.
Conclusion
Contactor coil voltage is importance aspect of the selection of contactors to be employed in any electrical system. Ensuring correct coil voltage selection will serve to ensure reliable operation, reduce poor system matching, and maintain excellent economy of energy. With good grasp of the importance of coil voltage, and being aware of the above parameters, selection of the right for your application will be a walk in the park, and will go a long way in helping maintain the optimum conditions and longevity of your electrical systems.
If you are seeking to buy contactors, or require aid in properly choosing contactors or other components of your electrical systems, it is best to consult with trusted supply man or manufacturer. Whether it is low voltage contactors, or high voltage you are interfacing with, you’d want to be sure you are using the contactor fit for your application’s safety and economy.