Lincoln Electric SVM127-A specification

B-7

OPERATION

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CIRCUIT BREAKER AND GROUNDING LEAD PRO- TECTOR (GLP) RESET SWITCH: These protection circuit devices are located on the front rail of the LN-9 model and bottom panel of the LN-9F models. See the topic "Circuit Protection and Automatic Shutdown" later in this section of the manual.

DIGITAL METER: A three-digit digital meter is provid- ed to set and monitor the welding procedure. The arc voltage is displayed in volts and the wire feed speed is displayed in inches/minute or meters/minute.

METER READING SWITCH, VOLTS AND WIRE SPEED CONTROLS: This four-position rotary switch is located to the right of the digital meter on LN-9mod- els and to the left of the digital meter on LN-9F models. When set to the "Volts" position, the meter reads the arc voltage setting as adjusted by the "Volts" control. The rated setting range for all the LN-9 models is 12.0 to 60.0 volts.

The three "Wire Speed" positions include an English position, for meter readings in inches/minute; and "LO" and "HI" range metric positions for meter readings in meters/minute. The wire feed speed setting is adjust- ed by the "Wire Speed" control. The rated setting range for all the LN-9 models are 50 to 600 inches/minute (1.27 to 15.2 meters/minute).

When using metric meter readings, set the switch to "LO" for more precise meter readings up to 393 in/min (9.99 m/min.). For higher wire feed speeds, the "LO" position will result in an over-range meter reading of

E.EEwhich indicates that the "HI" range, with single decimal place resolution, should be used. Similarly, EEE will be displayed on the English position if the set- ting exceeds 999 inches/minute.

The procedure adjustments can be made before or during the weld. This feature permits the operator to set the welding voltage and wire speed before welding and without assistance.

Once set, the control circuits of the LN-9 will continu- ously monitor the volts and wire speed and correct any deviation from the set value so there will be negligible change.

Should the range of the power source output voltage be such that the unit circuit cannot keep the arc voltage as set, the unit will stop welding shortly after the arc is struck. See the topic "Circuit Protection and Automatic Shutdown" later in this section of the manual.

SET-ACTUAL PUSHBUTTON: After the weld has been started, the ACTUAL voltage or wire speed can be read by pressing the pushbutton to the left of the meter. The METER READING switch must be set in the desired position. When the pushbutton is not being operated, the meter continues to read the SET value.

CIRCUIT PROTECTION AND AUTOMATIC SHUTDOWN

CIRCUIT BREAKER

The circuit breaker normally trips only when excessive loading in the wire feed cable or a defective motor or control component causes an overload. After allowing a minute for cooling, push in the circuit breaker button and weld. If it trips again, be sure the wire feed cable is clean and the proper size for the wire diameter being fed. Also look for excessive drive roll pressure and readjust if necessary. If the breaker still trips, look for a defective electrical component. When the circuit breaker is tripped, the digital meter is off and the trig- ger circuit will not operate.

POWER SUPPLY FUSE

The fuse on the PM power board inside the control box protects the power supply circuit. When the fuse is blown, the digital meter is off and the trigger circuit will not operate.

VOLTAGE PC BOARD FUSE

The 1/8 amp fast-blow fuse protects the LN-9 circuitry from damage that may result from a ground, or case, faulted control lead. If this fuse blows, the LN-9 arc voltage sensing lead circuit will be opened. See the topic "Automatic Shutdown" below.

MOTOR THERMAL PROTECTION

The temperature sensing thermal protector mounted in the motor frame opens the control circuit if the motor overheats. Excessive loading and/or very rapid trig- gering may cause overheating. The thermal sensor protects the motor without nuisance tripping. The ther- mal protector automatically resets itself after the motor cools sufficiently (may take 10-15 minutes). Reset time can be shortened by removing supply power to the LN- 9 and also by cooling the motor with an air hose or fan. When the protector is tripped, the digital meter is lit but there will be zero reading. The trigger circuit will not operate.

AVOIDING GROUNDING LEAD PROTECTOR (GLP) SHUTDOWN

The frames of all LN-9 wire feed units and drive motors are grounded to the frame of the power source by a lead in the control cable. An overload protector pre- vents welding current from damaging this lead if the electrode circuit touches the wire feeder frame while the gun trigger is pressed.

Lincoln Electric SVM127-A service manual Circuit Protection and Automatic Shutdown

Models: SVM127-A