What is the output of a transformer?
The output voltage of a transformer can be less than, greater than, or equal to the input voltage, depending on the ratio of the number of loops in their coils. Some transformers even provide a variable output by allowing connection to be made at different points on the secondary coil.
What does a control transformer do?
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.
How do you check the output of a transformer?
In output transformer testing, you use the voltmeter setting to check the output voltage while the transformer is connected to power. In a transformer continuity test, you disconnect the transformer from power and check resistance in both the input and output coils using the ohmmeter function.
What is the rotor of the control transformer consists of?
The control transformer consists of a three-phase, Y – connected stator and a single-phase cylindrical drum rotor. In normal usage, with the stator as the primary element, the unit is connected as shown in Figure 2.1. 4(a).
How do you turn off a transformer?
The utility has to replace the fuse to restore power, so if they want to cut power, they can simply disconnect the fuse, or even remove it entirely, resulting in no power going to the transformer. The usual way to turn you off is to pull the meter.
What are the types of Synchros?
It is classified into two types ; Torque Synchro and Control Synchro. The principles of Synchro are similar to those of an electrical transformer except that the iron core of Synchro consists of a rotor and a stator. Output voltage of Synchro varies in accordance with a rotation angle of a shaft.
How does the output of a control transformer work?
The output from the control transformer is either in phase or in anti-phase with the voltage applied to the transmitter rotor, depending upon the direction of rotation (clockwise or anti-clockwise) of the transmitter rotor (and directly upon the direction of rotation of the magnetic field in the stator of the control transformer).
Why are capacitors used in a control transformer?
Various filtering devices, such as capacitors, are used to minimize the variations in the output. This results in a more constant voltage or current.
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 should be considered when selecting a transformer?
Another consideration in the selection of the transformer is long wire runs. These occur if the control devices requiring power are located away from the transformer. When a long wire run is present, the resistance and capacitance cause a voltage drop to the control device. If the voltage drop is severe enough, the control device may not pick-up.