ESAB LAW 400, Руководство по обслуживанию

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COMPONENT DESCRIPTION LAW 400/500
The LAW welding rectifiers 500 are 6--pulse thyristor rectifier units intended for
semi--automatic welding. They are available for different mains voltages and with or without
integral cooling units: see the table in the spare parts list on page 55. The component
description below refers to the electrical circuit diagrams on page 6 to 12.
AP1
Circuit board with control electronics: see the function description
on page 18.
AP2 Suppression circuit board, see circuit diagram on page 30.
AP2 has been fitted with effect from machine no. 550 . . . . . . .
C1
Capacitor, 3 ← F 400 V. Start and run capacitor for fan motor EV1.
C2--C4
Suppression capacitors 0.1
←
F 250 V.
C5 Capacitor, 5 ← F 400 V. Start and run capacitor for pump motor M1. Only
in machines with water cooler.
C6 Capacitor, 6 ← F 400 V. For speed reduction of the cooling fan.
This capacitor has been fitted with effect from machine no. 512 . . . . . .
EV1
Fan
FU1
Circuit breaker, 10 A. Protects the 42 V supply to the wire feed unit.
HL1 Indicating lamp, 42 V, white. Lights when switch QF1 is in the ON
position.
KM2
Contactor 42 V 50 Hz. For speed control of the fan: see ST2 below.
This capacitor has been fitted with effect from machine no. 512 . . . . . . .
L1
Interphase transformer.
When connecting the interphase transformer to
the inductor, it is important that all parts are fitted exactly as shown in
Figure A on page 49.
L2 Inductor. When connecting the inductor, it is important that all parts
are fitted exactly as shown in Figures A, C and D on page 49.
M1
Pump motor, 230 V 50 Hz 0.2 kW. Only in machines with water cooler.
P1
Digital display. Accessory, see the list on page 40. The instrument is
described in the service manual for the MEK 4.
QF1 Main ON/OFF switch.
QF2 Cooling water pump switch. Only on machines with water cooler.
R1
Resistor, 0.43 τ .
RS1
Shunt, 60 mV / 600 A
ST1 Thermal overload cutout. Protects the machine against excessive
temperature. See the function description, item 6, on page 21.
ST2 Thermal switch. Controls the speed of fan motor EV1. The switch closes
when the temperature exceeds 80
_
C, energising contactor KM2. This
short--circuits capacitor C6, allowing the fan to run at full speed.
The switch opens when the machine temperature has fallen to 60
_
C.
LAW 400/410: ST2 is fitted in the interphase transformer winding, L1.
LAW 500/510: ST2 is fitted in the inductor winding, L2.
Thermal switch ST2 is fitted from machine no. 512 . . . . . . .