Another method of reducing the starting current
of a motor is to step down the voltage to the motor winding through the auto
transformer such as is called the “Auto Transformer Reduced Voltage Starter”.
This method is applied to high motor with large starting current.
Pressing the
start push button will energize contactor S and timer TR. Contactor Y is also
energized through normally closed contact TR (8-5). Instantaneous contact TR
(1-3) will close immediately to maintain the circuit continuously energized.
Contact Y (11-12) will open to ensure that contactor R will not be energized.
Contact S (1-2,3-4,5-6) and Y (1-2,3-4,5-6) will close to connect the auto
transformer T1, T2, and T3 to motor M, see Figure below (C). The motor M now
receives reduced voltage.
After few seconds the timer delay contacts TR (8-6) will close. This will be de-energized contactor Y. Contacts Y (1-2,3-4,5-6) will open. Contact Y (11-12) will close to energize contactor R. Contact R (1-2,3-4,5-6)will close to connect the motor M directly to the lines L1, L2,and L3. Contacts R (11-12)will open to de-energized contactor S. Contactor S (1-2,3-4,5-6) will open completely isolate the auto transformers T1, T2 and T3 from the lines L1, L2 and L3. The motor is now running at is final full voltage operation. See figure below (D).
Pressing the stop push button will de-energize contactor R and timer TR. Contact TR (1-3) will open to ensure that even if the stop push button is depressed, contactors S, Y, R and timer TR will not be energized. Contacts S (1-2,3-4,5-6), Y (1-2,3-4,5-6), and R (1-2,3-4,5-6) will open to bring the motor into stop condition. The circuit condition is brought back to the one as shown in figures (A) to (D).
Control Operation
Figures
below (A) and (B) illustrate the power and control circuit respectively of an
“Auto Transformer Reduce Control Voltage Starter”. The control circuit consist
of TR timers, contactors S, Y, and R.
(A) Power circuit of the “Auto Transformer Reduce Voltage Starter”.
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(B) Control circuit of the “Auto Transformer Reduce Voltage Starter”.
After few seconds the timer delay contacts TR (8-6) will close. This will be de-energized contactor Y. Contacts Y (1-2,3-4,5-6) will open. Contact Y (11-12) will close to energize contactor R. Contact R (1-2,3-4,5-6)will close to connect the motor M directly to the lines L1, L2,and L3. Contacts R (11-12)will open to de-energized contactor S. Contactor S (1-2,3-4,5-6) will open completely isolate the auto transformers T1, T2 and T3 from the lines L1, L2 and L3. The motor is now running at is final full voltage operation. See figure below (D).
(C) Power circuit connection or the Auto Transformer Reduce Voltage Starter”.
Pressing the stop push button will de-energize contactor R and timer TR. Contact TR (1-3) will open to ensure that even if the stop push button is depressed, contactors S, Y, R and timer TR will not be energized. Contacts S (1-2,3-4,5-6), Y (1-2,3-4,5-6), and R (1-2,3-4,5-6) will open to bring the motor into stop condition. The circuit condition is brought back to the one as shown in figures (A) to (D).
(D) Power circuit connection of the “Auto Transformer Reduce Voltage Starter at the final stage of operation.
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Nice post shared. Keep updating on your blogs.
ReplyDeletePower transformers in India | Transformer manufacturer in India
An auto transformer is the one that shares single winding and sometimes recognized as the Auto step down transformer. Their single windings perform the task for both the windings and give you the exact benefits like an ordinary device. They are economical in nature and occupy only limited space. There are a number of applications where an Auto Transformer is used especially in induction heater applications.
ReplyDeleteTransformer Manufacturers In India | Auto Transformer Manufacturers
It is a transformer in which both primary and secondary share a part of the winding and only one winding is wound on the laminated core.
ReplyDeleteTransformer Manufacturers In India | Transformer Manufacturers In Pune