Table of Contents
What is a control transformer used for?
A control transformer is a transformer that is used to step down the voltage to power the control devices of a circuit or machine. The reduced voltage provides a much safer environment for technicians working on the equipment.
What is the definition of control transformer?
A control transformer is an isolation transformer designed to provide a high degree of secondary voltage stability (regulation) during a short period overload condition typically referred to as inrush.
What class is a control transformer?
Class 2 transformers
For safety, control transformers should be UL or CSA recognized as Class 2 transformers. This safety rating guarantees the following safety specifications: A) The maximum control voltage is 30 VAC. If a voltage is 30 VAC or less it will not harm an individual.
How does a control transformer work?
Control transformer is a small dry-type transformer, which is mainly used to change the voltage of AC power. It is wound by an iron core and a coil. The alternating magnetic flux can pass through the primary coil and the secondary coil along the iron core, thereby achieving a closed magnetic circuit.
Where is the control transformer located?
Most Common Transformer Location The vast majority of the time, the transformer for the control panel is located inside the air handler. It’s often near the bottom bolted to a back wall or, if the system includes a furnace, to a side wall. The transformer may also be mounted to an outside wall of the air handler.
How do control transformers work?
A control transformer is designed to provide rated output voltage at full output VA. As the load decreases, the output voltage will go up. Conversely, increases in load will result in lower output voltages.
What is a Class 2 control transformer?
A Class II transformer is used to supply Class II circuits, commonly used on HVACR control systems. All Class II transformers are either inherently or non-inherently limited, meaning the maximum output current is limited either by the intrinsic coil impedance or by a fuse or circuit breaker.
Why do we need control transformer?
A control transformer is required to supply voltage to a load which requires significantly more current when initially energized than under normal steady state operating conditions. A control transformer is designed to provide secondary voltage stability under a short period of specific overload referred to as inrush.
What is the purpose of a control transformer?
A control transformer is a device used to transform or “step down” a high main circuit voltage to a lower voltage which is then used to operate the control or switching components of the main circuit.
What are the functions of a switch mode transformer?
Flexibility in terms of Power Conversion: Switch mode transformers can be used to create high conversions in voltage boosting applications as well as voltage step down applications. Understanding the basic functions of the switch mode transformer helps make it easy to use it in an application.
What are voltage ratings for control circuit transformers?
The methods of selecting transformer VA ratings addressed in this technical paper are applicable to 50…3000 VA control circuit transformers. The transformers used in this application fall in to the dry type insulation category. Typical primary voltages in the United States are 600, 480, 240, and 208.
What does a step down control transformer do?
The step-down control transformer would reduce the voltage to pushbuttons or PLCs to 120V or even 24V. A transformer with the reverse proportion of more turns on the secondary winding than on the primary is called a StepUp transformer. It will increase the voltage according to the ratio of turns.