Lincoln Electric SVM159-A service manual Theory of Operation, General Description

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E-2 E-2

THEORY OF OPERATION

FIGURE E.2 – INPUT VOLTAGE AND PRECHARGE

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					Main Switch Board
Input switch			Input			Primary
			Rectifier
						Current
						Sensor
			Reconnect
			Switch
						Primary
						Current
						Sensor
			Fan
			115VAC Fan Supply		CFanontrol	Primary Current Feedback(2)			IGBTDriveSignal
						Input Relay Control
			Auxiliary			Soft Start Control
220 VAC		Transformer				V/F Capacitor Feedback (2)
			40VDC	Machine Control Supply
				+15VDC, -15VDC, +5VDC
			Power
			Board	RS232 Supply +5VDC					Control Board
220	42VAC
				Can Supply +5VDC
Receptacle	65VAC
			DC			Arc		Electrode
			Bus			Link	Wire	Sense
			Board	40VDC
							Feeder
							Recp.		Thermostats
									2

Board	urrentC
Feedback

Choke

SenseVoltage

Output

21 Lead

Voltage

Sense

Recp.

Positive

Output

Terminal

Negative

Output

Terminal

Yellow

Thermal

LED

Status

Red/Green

LED

R232

Connector

Return

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GENERAL DESCRIPTION

The Power Wave semi-automatic power source is designed to be a part of a modular, multi-process welding system. Depending on configuration, it can support constant current, constant voltage, and pulse welding modes.

The Power Wave power source is designed to be used with the semi-automatic family of power feed wire feeders, operating as a system. Each component in the system has special circuitry to “talk with” the other system components, so each component (power source, wire feeder, user interface) knows what the other is doing at all times. These components com- municate with Linc-Net (a digital communications sys- tem).

The POWER WAVE 355/405 is a high performance, digitally controlled inverter welding power source capable of complex, high speed waveform control. Properly equipped, it can support the GMAW, GMAW- P, FCAW, SMAW, GTAW, and CAC-A processes. It car- ries an output rating of 350 Amps, 34 Volts at 60% duty cycle and 300 Amps, 32 volts at 100% duty cycle.

INPUT LINE VOLTAGE, AUXILIARY TRANSFORMER, & PRECHARGE

The POWER WAVE 355/405 can be connected for a variety of three-phase or single-phase input voltages. The initial power is applied to the 355/405 through a line switch located on the front of the machine. Two

phases of the input voltage are applied to the auxiliary transformer. The auxiliary transformer develops three different secondary voltages. The 115VAC is applied, via the main switch board, to the fan motor. The 42VAC is rectified and filtered. The 65VDC produced by the Bus board rectifier is used by the Bus board to provide 40VDC to the power board. 40VDC is also applied to the wire feeder receptacle. PW405 models have an additional 220VAC winding that is connected to a 220 AC receptacle.

The input voltage is rectified by the input rectifier and the resultant DC voltage is applied to the switch board through the reconnect switch assembly located at the rear of the machine. The reconnect switch connect the two pairs of input capacitors either in a parallel (lower voltage) or series (higher voltage) configuration to accommodate the applied input voltage.

During the precharge time the DC input voltage is applied to the input capacitors through a current limit- ing circuit. The input capacitors are charged slowly and current limited. A voltage to frequency converter circuit located on the switch board monitors the capacitor voltages. This signal is coupled to the con- trol board. When the input capacitors have charged to an acceptable level, the control board energizes the input relays, that are located on the switch board, making all of the input power, without current limiting, available to the input capacitors. If the capacitors become under or over voltage the control board will de-energize the input relays and the 355/405 output will be disabled. Other possible faults may also cause the input relays to drop out.

POWER WAVE 355/405