KEPCO BHK-MG 40W (Half Rack) Series - Manual (Page 27)

BHK-1/2-MG (OPR) 121313
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ping the circuit breaker. A flag is sent to the host computer via a dedicated line of the Status
and Remote On/Off port.
b. Overvoltage/overcurrent at the output. See PAR. 1.4.4
c. Uneven voltage in the pass and sink elements. Voltage is monitored across different tran-
sistors of the pass and sink elements. If uneven voltage continues for more than 20ms, the
pass element is cut off, the output capacitor is discharged, the POWER circuit breaker is
tripped to OFF and a flag is sent to the host computer on a dedicated line (Status and
Remote On/Off Port connector)
d. Input Voltage Selector set incorrectly. If the selector is set to 115V a-c and the input volt-
age is 230V a-c, the input circuit breaker will be tripped without delay. A flag is sent to the
host computer on a dedicated line (Status and Remote On/Off Port).
e. AC line failure. If AC line is missing for more than 50 ms, a flag is sent to the host computer
on a dedicated line (Status Port connector). In addition, if the jumper at A3-JP2 is installed
(default state), the pass element is cut off, the output capacitor is discharged, and the
POWER circuit breaker is tripped to OFF.
f. Interruption between the sensing and corresponding power output terminals. If there
is an interruption between the sensing and power terminals, two diodes connected in parallel
between the sensing lead and the corresponding power lead (one forward biased and one
reverse biased), allow the power supply to continue to function.
g. Overload of the main or auxiliary power transformer. If input current of the main trans-
former exceeds 1.1A a-c @ 115V a-c or 0.6A a-c @ 230V a-c, the input POWER circuit
breaker is tripped to OFF, the pass element is cut off, the output capacitor is discharged, and
a flag is sent to the Status Port connector. The reaction time is inversely proportional to the
input overcurrent: from a minimum of 10ms for 10 times nominal current, to a maximum of
100 seconds for 25% above nominal current.
If input current of the auxiliary power transformer exceeds a predetermined value, the PTC
(Positive Thermal Coefficient) thermistor (in series with the primaries of the auxiliary trans-
formers) resistance will increase, thus reducing the voltage across the primary of the corre-
sponding transformer. If this occurs, the pass element will be cut off. In some circumstances,
depending upon which transformer is involved and whether an overcurrent condition is
detected during or after power-up, the input circuit breaker may trip OFF.
h. Current Limit. The current through the pass and sink elements is monitored. If this current is
1.5 times larger than the nominal value for more than 20ms, the pass element is cut off, the
output capacitor is discharged, and the POWER circuit breaker is tripped to OFF. A flag is
sent to the host computer via the Status and Remote On/Off Port.
1.4.10 ANALOG READBACK AND FLAG SIGNALS AVAILABLE FOR CUSTOMER USE
Some internal signals produced by the unit are available at connector A2J5 for either monitoring
or testing purposes. Refer to Table 1-3 for a description of available signals.
1.4.11 EXTERNAL TRIGGER PORT
The External Trigger Port provides two functions: a shutdown input can be used to immediately
shut down the power supply output (see PAR. 3.2.7.3) and a trigger input can be used to restore
the output to previously defined settings (see PAR. 3.3.4).