Lincoln Electric SVM135-B Power Source General Description, Input Voltage and Precharge

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E-5

THEORY OF OPERATION E-5

FIGURE E.4 — INPUT VOLTAGE AND RECHARGE.

									MAIN
									TRANSFORMER	CURRENT
										SENSOR
						LEFT
						SWITCH
						BOARD				OUTPUT
						PWM				TERMINAL
	INPUT		INPUT			DRIVE
	CONTACTOR		RECTIFIER
				R	S
				E	W
				C			PRIMARY
				O	I		CURRENT
				N	T		SENSOR
				N		CAPACITOR
				E	C	VOLTAGE
				C	H	FEEDBACK
				T
P S
O W
W I
T						RIGHT				CHOKE
E C	I	B
R H						SWITCH
	N O
						BOARD
	P A
	U R									OUTPUT
	T	D	CONTROL SIGNALS			PWM	CAPACITOR			TERMINAL
						DRIVE	VOLTAGE			THERMOSTATS
	#1 AUX.						FEEDBACK
			RECTIFIER
	TRANS.
			65VDC							CURRENT FEEDBACK
							CONTROL BOARD
AUX.										VOLTAGE FEEDBACK
RECONNECT	#2AUX.
	TRANS.		FAN
			MOTOR	POWER
				BOARD
						40VDC				STATUS
						WIRE FEEDER	RS232	VOLTAGE	THERMAL	LIGHT
	115VAC							SENSE	LIGHT
						RECEPTACLE	CONN.
	RECEPTACLE							RECEPTACLE

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POWER SOURCE GENERAL DESCRIPTION

The Power Wave 455 is an inverter based welding power source that is designed to be part of a modular, multi-process welding system. It is a high performance, digitally controlled inverter capable of complex, high-speed waveform control. With the appropriate modular components it can sup- port constant current, constant voltage and pulse welding processes. The output rating is 450 amps at 38 volts with a 100% duty cycle.

INPUT VOLTAGE AND PRECHARGE

The Power Wave 455 can be connected for a variety of three phase voltages. Refer to Figure E.4. The initial input power is applied to the Power Wave 455 through a line switch located on the front of the machine. Two phases of the three-phase input power is applied to the input board and both auxiliary transformers. The vari- ous secondary voltages developed by the #1 auxiliary transformer are applied to the input board, the power board rectifier and the fan motor. The 115 VAC secondary

voltage developed by the No. 2 auxiliary transformer is applied to the 115 VAC receptacle.

The 65 VDC produced from the power board rectifier is utilized by the power board to provide various DC voltages for the con- trol board and wire feeder.

The two phases which are connected to the input board, through the power switch, are connected to the input rectifier. During precharge or “soft start” these two phases are current limited by the input board. This AC input voltage is rectified, and the resul- tant DC voltage is applied through the reconnect switches to the input capacitors located on the switch boards. The control board monitors the voltage across the capacitors. When the capacitors have charged to an acceptable level, the control board signals the input board to energize the main input contactor making all three phases of input power, without current limit- ing, available to the input capacitors. At this point, the Power Wave 455 is in the “Run Mode” of operation. If the capacitors become under or overvoltage, the control board will signal the input board to de- energize the main input contactor, and the Power Wave 455 will be disabled.

POWER WAVE 455/POWER FEED 10