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16. Trouble Shooting
In the event a problem arises during operation, inspect the instrument by referring to the following table and call our office in the neighborhood.
Problem
Point to be inspected
Remedial measure
1
Output has stopped. 1) Alarm monitor O.C. lights.
It appears that excessive current flowed for some reason. For pure metal
heater or transformer load, set longer soft start time. If alarm lights
again, turn power off to bring power regulator to 0%. Then, turn power
on again.
2) Alarm monitor O.H. lights.
Thyristors might be overheated. Turn power off to lower instrument
temperature and turn power on again. If monitor lights again soon after
situation is normalized, too large load current of thyristor or poor heat
radiation is suspected. Use with reduced load current or improve radiation
conditions.
3) Alarm monitor FUSE lights.
Rapid fuse for thyristor protection might be fused. See if there is short-circuit
of load or ground fault and replace with new fuse after removing cause of
problem.
4) Alarm monitor THY lights.
If load current is zero, load is open. Check for break of load.
5) PL lamp (green) does not
light.
Examine power supply and check the power source side if power is off. In
case power is on, instrument trouble is suspected
6) Are control input signals being
received?
Measure input level across terminals C1 and C2 by using a tester, for
example. If there is no input signal, check the supply source of signal such
as a controller. In case regular signal is found, check connection and set
values of power regulators. When they are correct, instrument trouble is
suspected.
2
Output
keeps
being produced.
1) Alarm monitor THY lights.
Thyristor short-circuit or open load is assumed.
2) Is load circuit open?
When load circuit is open, panel meter and tester will show high voltage.
Examine load circuit. (This sometimes happens during trial run.)
3) Base power or low power
regulator is connected.
It is for preventing minimum value of output from being 0.
Detach low power regulator and recheck.
3
Maximum output
has lowered.
1) Check settings on scales of
various power adjusters.
Check scales of internal and external power adjusters. Set at 100% and
see how output will change.
2) Check control input signal
Check if control input signals have been received hundred percent.
3) Addition of current limiting
circuit.
Examine scale of current limit setting device. Set at 100% and confirm
output voltage/current. If output current flows fully at rated level, current
limiting function is working.
Load is far heavier than rated for PAC27.
4) Constant power (power FB)
control
Rated voltage x rated current x 1/2 should be in proportion to control
input signal. Measure output current. If more current than 1/2 of the
rating flows, maximum output will fall.
5) Check output voltage meter.
Indicated value may change depending on types of meters. Make sure
to use true RMS type or movable iron piece type meter. When voltage
is measured by using general digital or analogue tester, average value is
converted into true RMS for display. Hence display error increases. (In the
case of 200 V power supply, display error will come to 43 V maximum.
4
Fuse breaks
(FUSE lights) or
excessive current
protective circuit
(O.C.) is activated
frequently.
1) Are load capacity and PAC27
capacity suitable?
In case load rate exceeds 100%, output should be lowered by the use of
power adjuster.
2) In the case of load with large
rush current such as pure metal
heater.
Set longer time for soft start. If it does not work, add current limiting
function (option) or replace PAC27 with one which has a larger current
rating.
3) Transformer is used.
Set longer time for soft start. Try to reduce load relatively to transformer
capacity. If noise is assumed to be cause of erroneous operation, connect
capacitor (250V AC 0.1 μF) across terminals R and T.
