Lincoln Electric SVM149-A service manual Main Transformer, Return Return to Section TOC

Models: SVM149-A

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Section TOC

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E-4E-4

THEORY OF OPERATION

FIGURE E.4 – MAIN TRANSFORMER

INPUT 115/230/1/50/60 VAC

L1 SW1 A 300uH

B

RL3

 

RL2

R1

 

RL2

10/10W

 

F1

 

1A/250V

RL2

 

 

C26

AC

AC

 

CP

CP

CP

CP

CP

 

AC

AC

 

R1

CP

R2

15K/3W 15K/3W

1500uF/250V

+

C1a,b

+

C2a,b

Q1a,b,c

D10

Lout

BS1

 

IRG4BC30W

WRK

 

 

240uH

8A

 

 

 

 

 

T2

SEC

 

+12VDC TRANSFER

 

PRI

 

 

 

C12

D11

 

RL1

NZL (2)

 

 

 

 

 

 

 

C14

 

WORK CLAMP

V1

RL2

RL1

 

R24

Q2a,b,c

6.8k/5W

IRG4BC30W

 

FN1

230VAC

V2

 

 

115VAC

L1

T1

230V

RL1

1500uF/250V

 

SHUNT

EL (3)

C13

SH-

SH+

 

 

 

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NO

COM

NC

Purge Switch

115V

L1

Input

Voltage Board

12VDC

Air

Solenoid

1

CN1

15VAC

 

CN2

 

 

 

 

 

 

 

 

 

 

 

 

CN3

1

 

9

 

 

 

 

 

 

 

 

 

 

 

 

1

2

15VAC

 

10

 

 

 

 

 

 

 

 

 

 

 

 

2

3

SAFETY

 

5

 

 

 

 

 

 

 

 

 

 

 

 

3

4

+28VDC

 

6

 

 

 

 

 

 

 

 

 

 

 

 

4

5

SEC GND

 

3

 

 

 

 

 

 

 

 

 

 

 

 

Main Inverter Board

6

OVLOAD

 

22

 

 

 

 

 

 

 

 

 

 

 

 

7

115/230

 

2

 

 

 

 

 

 

 

 

 

 

 

 

 

8

+12VDC

 

20

 

 

 

 

 

 

 

 

 

CN1

 

 

 

 

 

 

 

 

15 16 12 18 14 1

 

 

 

 

 

 

 

 

 

4

 

 

 

 

 

11 4

13 7

19 24 21 23 8

17

1

2

3

 

PS2

PS1

SEC GND OVLOAD

SAFETY

V+ EV1 +15Vrms

+12VDC

+8V SW +12VDC SW

SEC GND

OVLOAD

TRANSFER SW

TRANSFER

SOL 1 DRIVER

V OUT OUTPUT TRIGGER SOL 2 DRIVER

 

POT WIPER

POT CW

POT CCW

 

CN1

8

6

17 9

3

1

2

18 14 7

15 4

11 5

16 10 12 13

 

23 22 24

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Display LED's

Output Control

Control Board

PT

12VDC Solenoid 2

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MAIN TRANSFORMER

The pair of IGBTs act as a switch assembly. This assembly feeds a primary winding of the main trans- former. When current is pulsed through this primary winding, a resultant current is produced on the sec- ondary winding of the main transformer. The DC cur- rent flow through the primary winding is redirected or “clamped” back to the filter capacitors when the IGBTs are turned off. This is needed due to the inductance of the transformer primary winding.

The primary current also passes through the current transformer, which sends a signal to the control cir- cuits of the inverter board. This signal and the control circuits limit the maximum primary current flow

through the IGBTs. The pair of IGBT’s are fired at 15 microsecond intervals, creating a constant 66.6KHz output.

The secondary portion of the main transformer is made up of one winding. This winding supplies the electrode-to-nozzle and electrode-to-work voltages and the resulting currents. This high current winding is capable of supplying maximum output current during the cutting process. The output current is regulated via pulse width modulation. The control circuitry, on the inverter board, receives a signal from the control board and regulates the output current to the desired level.

PRO-CUT 25

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Lincoln Electric SVM149-A service manual Main Transformer, Return Return to Section TOC