Lincoln Electric SVM151-A service manual Theory of Operation, General Description

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E-2 E-2

THEORY OF OPERATION

FIGURE E.2 – INPUT POWER SOURCE, CONTACTOR AND DC BUSS POWER SUPPLY BOARD

MULTI-WELD 350 BLOCK LOGIC DIAGRAM

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+

DC

POWER SOURCE

(EXTERNAL)

_

INPUT			LEFT AND RIGHT
DIODES	INPUT		CHOPPER MODULES
	CONTACTOR
		CR1
			IGBT		FREEWHEELING DIODE
			CHOPPER MODULE
		INPUT			CHOKE
	CAPACITORS
	ON/OFF		IGBT		FREEWHEELING DIODE
	MODE
	SWITCH	20	CHOPPER MODULE
	(1/2)
		VDC		ON/OFF	VOLTS AMPS
		x 2		MODE
				SWITCH
				(1/2)
				GATE
			ANALOG	SIGNALS
	DC	40			WELD
	BUS	VDC	CONTROL VOLTAGES		CONTROL
				REGULATED
	POWER		POWER	FAN	BOARD
	SUPPLY		SUPPLY
	BOARD		BOARD

TO ELECTRODE

CABLE

SHUNT+

CURRENT FEEDBACK

TO WELD CONTROL BOARD

REMOTE

RECEPTACLE

CCSLOPE

(STICK/GOUGE or PIPE)

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40 VDC	ARC OUTPUT		HOT
15 VDC				THERMAL
	FORCE	CONTROL	START	LIGHT
	CONTROL
	CR1
	COIL
PERIPHERAL
BOARD	INDICATOR
	INPUT
	LIGHT

-

WORK

GENERAL DESCRIPTION

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The MULTI-WELD 350 Converter uses a single DC input power source to provide up to 350 continuous amps for positive polarity stick, wire processes, and arc-air gouging. The machine converts higher volt- age/lower current DC input power to lower voltage/higher current DC output power with over 90% efficiency. This DC output is controlled by Chopper Technology to produce DC current for multi-purpose welding applications.

INPUT POWER SOURCE, CONTACTOR AND DC BUSS POWER SUPPLY BOARD

The Multi-Weld 350 receives DC input power from an 80 VDC buss Multi-Source (recommended), although other external DC sources such as the Lincoln Electric DC-1000, DC-655, or DC-600 can be used if they pro- duce 50 VDC or above.

The +50 VDC supply voltage is applied to the input contactor via two large input diodes. The input contac- tor establishes the electrical connection between the Multi-Weld 350 and the power source when the ON/OFF MODE switch is activated in either the con- stant current (CC-stick) mode or the constant voltage (CV-wire) mode.

A 40 VDC Buss Power Supply Board supplies 40 VDC power to the Analog Control Power Supply Board, which in turn feeds regulated voltages to a Weld Control Board and 15 VDC to the Peripheral Board. The Peripheral Board powers the input contactor coil and the input indicator light on the front panel. The 40 VDC is also supplied to the Peripheral Board and is passed on to the Weld Control Board.

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NOTE: Unshaded areas of Block Logic Diagram are the subject of discussion.

MULTI-WELD 350