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Hypertherm HT4400 HySpeed Plasma Arc Cutting System User Manual

Page 122

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MAINTENANCE

HT4400

Instruction Manual

5-31

3

Phase Loss Detection Board PCB21 - Status Indicators and Operation

Operation

The phase loss detection circuit looks at the incoming voltage and verifies that the voltages between the 3-wire
inputs are within +/- 15% of each other.

• After contactor CON1 closes, opto-coupler U1 on PCB21 is activated, shorting pins 1&2 of PL1 together

and illuminating LED1.

• If LED1 does not illuminate:

• Verify that voltages across points A B and C, phase-to-phase are approximately 255 VAC. If voltages

are not within +/- 15%, LED1 will not illuminate. Check the incoming line voltage and the contacts on
CON1.

• Check PCB21 fuses F1-F3. If any of the fuses are open, then PCB21 is faulty.

• Check jumper on P2 and verify that the jumper is set for 265V.

Phase Loss Board PCB21 location on chopper CH4 -
See page 6-3 for location of CH4

F1

A

F2

B

F3

U1

C

LED1

P2

P2 Jumper
for 265 V