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HSF-A 1500W 010421
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3.7.2 CURRENT LIMIT SETTING AND EXCESS POWER PROTECTION
The output characteristic of the power supply is square type, with default current limit at 105% of
nominal current.
If a current limit lower than the default is needed, a 0.5 to 4.5 kohm resistor can be installed on the
main printed circuit board at location R9. A resistor of 1 kohms limits the current to about 20%, 2.5
kohms to about 50%, 4 kohms to about 80% of the unit’s nominal current.
In the rare case when both the output voltage and current are above their nominal values, excess
power protection may shut down the unit. This happens when the internal power module power
level exceeds 105% of nominal power or, respectively, 1530W for the 24V model or 1550W for the
36, 48, 60V models.
To restart (reset) the unit, press and release the OUTPUT RESET switch on the front panel or use
the remote on/off feature (see PAR. 3.6). The unit may also be restarted by turning the POWER
ON/OFF switch to OFF, waiting 40 seconds, then setting the POWER switch to ON.
3.7.3 FAN FAILURE
A fan failure causes the output to shut down and the fans to turn OFF. Fan failure and all the other
protection circuit operations produce an alarm (see PAR. 3.8.2). To restart (reset) the unit, press
and release the OUTPUT RESET switch on the front panel or use the remote on/off feature (see
PAR. 3.6). The unit may also be restarted by turning the POWER ON/OFF switch to OFF, waiting
40 seconds, then setting the POWER switch to ON. If fan rotation is out of specification the power
supply will not recover.
3.8
ALARM SETTINGS
3.8.1 VISUAL ALARM.
The front panel VDC ON/ALARM indicator can be configured to light red if a) the respective power
supply output voltage is lost, b) the unit is reset (local or remotely) or c) if the POWER switch is
set to OFF (indicator lights red for 30 seconds after setting to OFF). This feature is enabled when
DIP switch 1, position 8 set to ON (factory default, see Figure 5 for switch location).
3.8.2 ALARM SIGNALS.
Either of two options are available for signalling alarms: isolated relay contacts (factory default,
PAR. 3.8.2.1) or logic level alarm sPF (PAR. 3.8.2.2).
3.8.2.1 INTERNAL ISOLATED RELAY ALARM
The first option, the factory default setting, uses an isolated internal relay offering normally closed
(NC) and normally open (NO) contacts referenced to an isolated common (AL COM). These con-
tacts may be used to configure “close on failure” or “open on failure” alarm circuits. (Refer to the
Series RA 19-4C Manual for alarm configurations for multiple HSF power supplies.) Setting posi-
tion 6 to OFF and 7 to ON (factory default) selects this option. The NC (pin 6of the rack adapter I/
O connector) and NO (pin 7) signals are referenced to Alarm common (pin 14).
3.8.2.2 OPTICALLY-COUPLED LOGICAL ALARM
This ±PF signals, available in older non-A suffix HSF 1200/1500W models are not available in the
HSF-A 1500W series. Therefore DIP switch SW1 position 6 should always be set to OFF and
position 7 set to ON.