WTC MedWeld 4000, Руководство оператора

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Advanced Software Features
MedWeld 4000 Operator’s Guide Modified: 9/17/08 7 - 11
M-032116 Programs #T03300, #T02300 and #T02400
Danger!
DO NOT disable short detection (by setting
this parameter to DISABLE) for normal
operating conditions.
When disabling short detection, the control will
not shunt trip the circuit breaker in case of an
SCR short. The control will not detect situations
such as a catastrophic SCR failure. This can
cause tool damage, and create the potential
for serious injury or death.
When the processor detects no voltage drop across the SCRs during four
out of seven half-cycles, it examines the primary current to determine
whether the drop was due to a shorted SCR:
• Primary current exceeding a preset amperage indicates a shorted
SCR. The weld processor immediately generates a SHORTED SCR
fault.
• If the primary current is less than a preset amperage, the processor
checks the SCR Cycle Limit parameter to determine whether the
voltage drop was due to a shorted SCR or shunting current.
• The SCR Cycle Limit parameter sets the maximum number of
consecutive cycles where a shorted SCR condition (without
current) can occur before the breaker is tripped. The control then
generates the appropriate fault (either SHORTED SCR or
CURRENT SHUNTING).
WARNING! If the control detects a shorted SCR condition
with current for four out of seven half-cycles,
the control will trip the breaker, regardless of
the programmed value of this setup parameter.
• If the control detects no primary current for 3 or more consecutive
cycles, it generates the WELDER CURRENT SHUNTING fault.
(If the SCR is shorted or current is shunting, primary current will
not be detected.) This fault conditions indicates that shunting was
detected for more than 3 cycles
but less than the number of cycles
programmed in the Shorted SCR Cycle Limit setup parameter.