15-10-2012, 12:52 PM
DESCRIPTION OF WIRING DIAGRAM OF AUMA ACTUATOR
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General Description:
Any actuator closes the valve on clockwise rotation and opens the valve on anticlockwise rotation. The wiring diagram shows the actuator at rest in an intermediate position.
The torque switches DSR & DOEL will act as overload protection after full travel of the actuator.
DSR (Torque switch – closing - clockwise rotation) interrupts the control circuit on reaching the set torque and hence the actuator will be switched off.
WSR (limit switch – closing- clockwise rotation) serves for indication and it must be set to operate just before reaching end position CLOSED.
Similarly DOEL (Torque switch - opening - counter clockwise rotation) interrupts the control circuit on reaching the set torque and hence the actuator will be switched off.
WOEL (Limit switch, opening, counter clockwise rotation) serves for indication and it must be set to operate just before reaching the end position OPEN.
There are two contactors in the circuit to reverse the direction of rotation of the motor actuator. These two contactors are named as K1 - for closing the valve and K2 - for opening the valve.
Let us identify how many contacts are there in each contactor, their status i.e. whether normally open (NO) or normally closed (NC) as per the wiring diagram shown (with the actuator at rest in the intermediate position) and also the function of each contact.
Power Supply circuit details:
3 - Ph, 440 Volts supply will be given to the actuator motor through the main switch Q1; power supply fuses F2, either of the contactors K1 or K2 and through the draw out type isolator (XA.)
Motor body also is earthed to the plant earth PE.
230 Volts Single phase supply from L1 is given to the space heater in the control panel.
Details of control supply and indication circuits (230 Volts AC):
a) Closing & opening circuits of the actuator through the thermo switches F1 (TH).
b) Close and Open lamp indicating circuits.
c) Fault indicating lamp whenever the actuator trips on torque switch contacts.
d) Flicker bus supply for the close and open lamps during operation of the actuator.
Contactor K1 has got three auxiliary contacts in the circuit as detailed below:
1. One contact along with the push button CLOSE-REMOTE- S9 (in open position) to act as the holding contact for the closing circuit.
2. One contact in the opening circuit (in closed position) in series with the opening coil of the contactor K2.
3. One contact in the “close” lamp indication circuit (in open position) through the Blinker transmitter S5 (BL).
Contactor K2 also has got three auxiliary contacts in the circuit as detailed below:
1. One contact along with the push button OPEN-REMOTE-S10 (in open position) to act as the holding contact for the opening circuit.
2. One contact in the closing circuit (in closed position) in series with the closing coil of the contactor K1.
3. One contact in the “open” lamp indication circuit (in open position) through the Blinker transmitter S5 (BL).
Description of closing operation:
When the close push button S 9 is pressed, supply to the contactor coil K1 is made through F1 (TH) Thermo switches – Stop PB S 8 – S 1 (DSR) the torque switch (closing, clockwise rotation) in closed position through terminals XA 1 & XA 2 – closed contacts XA 9 & XA 10 of close limit switch S 3 (WSR)-closed auxiliary contact of contactor K2 with terminals 21 & 22 and hence the coil K1 gets energized and the power contactor K1 closes making the power supply circuit through to the motor, by which the motor starts rotating in the clockwise direction.
Description of opening operation:
When the open push button S 10 is pressed, supply to the contactor coil K2 is made through F1 (TH) Thermo switches – Stop PB S 8 – S 2 (DOEL) the torque switch (opening ,counter clockwise rotation) in closed position through terminals XA 5 & XA 6 – closed contacts of open limit switch S 4 (WOEL) XA 13 & XA 14 -closed auxiliary contact of contactor K1 with terminals 21 & 22 and hence the coil K2 gets energized and the power contactor K2 closes making the power supply circuit through to the motor, by which the motor starts rotating in the counter clockwise direction.
The push button S 10 will be pressed once and released thus giving opening impulse to open the valve. The motor will be running in the open direction till it reaches its end position and the torque switch (opening, counter clockwise rotation) S2 (DOEL) interrupts the control circuit on reaching the set torque. (This continuous rotation of the motor even after releasing of the push button is achieved because of the closed auxiliary contacts 13 & 14 of the main contactor K2 due to picking up of the contactor K2, which provides the holding circuit for the control supply even after releasing the close push button).
When the torque switch S2 (DOEL) acts the terminals XA 5 & XA 6 get open circuited and the control supply to the contactor coil K2 gets interrupted. Hence the contactor K2 drops interrupting the power supply to the motor and the motor stops rotating. Open limit switch S 4 (WOEL) operates shortly before reaching the end position OPEN, thus making the indicating circuit through to the open indication lamp through the terminals XA 15 & XA 16 and thus the open indication lamp glows.