Lincoln Electric SVM159-A service manual Table of Contents Theory of Operation Section

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Section E-1Section E-1

TABLE OF CONTENTS

-THEORY OF OPERATION SECTION-

Theory of Operation	Section E
General Description	E-2
Input Line Voltage, Auxiliary Transformer and Precharge	E-2
Switch Board and Main Transformer	E-3
DC Bus Board, Power board and Control Board	E-4
Output Rectifier and Choke	E-5
Thermal Protection	E-6
Protective Circuits	E-6
Over current Protection	E-6
Under/Over Voltage Protection	E-6
Insulated Gate Bipolar Transistor (IGBT) Operation	E-7
Pulse Width Modulation	E-8
Minimum/Maximum Output	E-8

FIGURE E.1 – PW-355 BLOCK LOGIC DIAGRAM

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Main Switch Board

Input

		Input switch		Rectifier			Primary
							Current
							Sensor
				Reconnect
				Switch
							Primary
							Current
							Sensor
				Fan
e				115VAC Fan Supply		CanFontrol	Primary Current Feedback(2)		IGBTDriveignalS
	{						Input Relay Control
P				Auxiliary			Soft Start Control
		220 VAC Transformer					V/F Capacitor Feedback (2)
o
w
r					Machine Control Supply
W				40VDC
					+15VDC, -15VDC, +5VDC
a				Power
v				Board				Control Board
e					RS232 Supply +5VDC
4		220	42VAC
0					Can Supply +5VDC
5		Receptacle	65VAC
l				DC			Arc	Electrode
o
n
y				Bus			Link	Sense
				Board	40VDC		Wire
							Feeder
							Recp.		Thermostats
									2
							To
							Feeder

POWER WAVE 355/405

To Control

Board

Feedback Current

Choke

SenseVoltage

Output

21 Lead

Voltage

Sense

Recp.

Positive

Output

Terminal

Negative

Output

Terminal

Yellow

Thermal

LED

Status

Red/Green

LED

R232

Connector