9
SECTION 3
P1350 AC POWER SUPPLY OPERATING INSTRUCTIONS
3.4
OPERATION UNDER FAULT CONDITIONS.
The P1350 AC source incorporates three levels of over current protection. The first is a fold back circuit
that reacts to long term RMS over current. In the event that the load applied is outside the range of the
power source, the output voltage will decrease or “fold -back” in order to maintain the current. During
fold back the output waveform remains sinusoidal. This can be a useful feature for starting AC induction
motors and other types of motion related loads.
In the event the load becomes short circuited the amount of fault current could rise to levels high
enough to damage the output semiconductors of the power source. The current of the output stage is
monitored on a cycle by cycle basis at the 20KHz switching frequency. If the peak current exceeds an
unsafe value, a logic signal is sent to the drive circuits that initiates a controlled shutdown of the output
stage. This circuit can respond within 20usec. The action of this overload circuit is latching. The input
power must be cycled to reset the power source. Allow at least 20 - 30 seconds for the internal soft start
circuit to reset. Further information is provided in this manual under operating considerations.
The final form of protection is provided by a 25 amp input fuse. This fuse is employed primarily to
provide fire protection in the event of an internal failure of the power source. Failure of this fuse typically
indicates that an internal problem may exist.
!
CAUTION
In the event the fuse is to be replaced disconnect power before removing the fuse cover
.
This fuse is rated at 25A and 132V minimum and
must
be replaced with the same type and voltage
rating only! If a replacement fuse blows again the unit should be returned to Behlman for service.
3.5
TROUBLE SHOOTING
In the event a problem is encountered refer to the chart below :
PROBLEM
POSSIBLE CAUSE
No output, meter indicates 000
Adjust output control, check if overload latch LED is on. See section 4.
Load does not operate, unit
indicates desired output.
Check that load is switched on. Check that the load is connected between HI and
Lo output terminals vs. HI and GND. terminals. See section 3.2.
Output voltage drops when load
is connected.
Check load current to insure that the rating of the power supply is not exceeded.
This may be indicated by a “blinking” or steady constant current LED.
Output drops to zero when load
is connected, Overload LED is
on.
Load in-rush or surge current has exceeded the short circuit limit for the power
supply. See section 4 for techniques to limit in-rush current.
Unit is Dead, no display or fan
sound.
Blown input fuse. Check and replace per para.3.4. If fuse blows repeatedly ,
remove unit from use and refer to qualified service personnel or Behlman service
dept.
