Control Transformer Technology Parameters
Control transformers are used to convert low voltages of up to 480 volts to the standard 120 / 240 volts required for control equipment when used in a circuits powered by a higher voltage. Control transformers usually operate at a power rating of around 10 KVA, though larger ratings can be used when a higher load is required. Control transformers are designed to ensure safety by providing low voltage shut off capabilities, over voltage protection, current limit and ground fault protection. These features help to protect the equipment from total failure and prolong lifespan.
Control transformers utilize a core and winding technology that produce an output of the desired voltage at a low current. The voltage is usually about 1/4 to 1/2 of the input voltage, allowing the control equipment to be operated at a safe level. Standard control transformers are typically tapped in 15 steps, in order to provide flexibility in the control voltage to suit a range of control circuit requirements.
Control transformers require careful consideration as they have to be capable of coping with many types of loads which can change over time. This includes the amount of load, operating speed and temperature of the load. Generally, the current is the most important factor in selecting the size of the control transformer. This can be calculated by dividing the rated load current by the primary voltage.
The type of load on the control transformer also needs to be considered. Resistive, inductive and capacitive loads will all require different control strategies, so it is important to ensure that the correct transformer is chosen for the specific application.
In order to protect the control transformer from overheating, a cooling fan or liquid coolant should be used. Cooling fans are usually found in enclosed units, but liquid coolants are usually used for outdoor applications. The cooling rate will depend on the design, temperature and load of the transformer. When selecting the correct type, it is important to ensure that it is adjustable to ensure full and safe operation of the control equipment.
Control transformers can also be adapted to suit conditions such as high altitude or high temperatures. High altitude applications require larger control transformers due to the decrease in capability with an increase in altitude, whilst equipment in high temperature environments require cooling systems such as liquid coolants to prevent overheating. In both of these cases, it is important to ensure that the right transformer is chosen to ensure safe operation and suitable output.
The location of the transformer should also be considered when selecting the right one. Transformers located in a damp and dusty environment may require different protection measures, such as additional enclosures or special interior coatings. Correct installation of the control transformers is important to ensure effective operation, and can involve supporting brackets or suspension brackets to prevent excessive vibration and reduce noise.
Control transformers are a vital component in industrial equipment, but it is important to select the correct transformer for the application to guarantee safe and reliable operation. By being aware of the differences between resistive, inductive and capacitive loads, and considering the factors such as the temperature, location and altitude of the equipment, an adequate selection of the correct control transformer can be made. And a reliable and safe output can be guaranteed.
