12
HSF (M) 300W 042315
3.7.2 OVERCURRENT SETTING AND PROTECTION
The output characteristic of the power supply is a square type, and the unit is set to produce an
alarm (see PAR. 3.8.2) and shut down if output current exceeds specifications (see Table 2) for
more than 30 seconds. After the cause of overcurrent is removed, the power supply output is auto-
matically restored.and shut down if output current exceeds specifications (see Table 2) for more
than 30 seconds. After shut down, reset (restart) the unit per PAR. 3.6.
3.7.3 FAN FAILURE
A cutoff of the fan supply voltage or a decrease in fan speed 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). After shut down, reset (restart) the unit per PAR. 3.6. If fan rotation is out of specifica-
tion the power supply will not recover.
3.7.4 UNDERVOLTAGE
M MODELS ONLY:
If power supply output voltage either falls below 80% of the programmed (set)
value, or if output voltage is programmed below the minimum values listed in Table 4, an alarm
occurs if the internal relay alarm (factory default, see PAR. 3.8.2.1) is enabled. After shut down,
reset (restart) the unit per PAR. 3.6. To enable the alarm function when operating below the mini-
mum values listed in Table 4, refer to PAR. 3.8.2.2 to configure the optically-coupled alarm.
MZ MODELS ONLY:
If power supply output voltage falls below 80% of the programmed (set)
value, an alarm occurs. After shut down, reset (restart) the unit per PAR. 3.6.
3.8
ALARM SETTINGS
3.8.1 VISUAL ALARM.
When the unit is connected in a parallel configuration, the front panel VDC ON/ALARM indicator
can be configured to light red if the respective power supply output voltage is lost or if the POWER
switch is set to OFF. This is enabled when DIP switch 1, position 8 set to ON. This can be useful
to indicate the loss of output voltage from one parallel-connected power supply that may not be
readily apparent. The visual alarm is normally disabled: DIP switch SW1, position 8 set to OFF
(factory default); requires minimums per Table 4 if enabled (see PAR 3.9). Only one of these two
must be enabled, the other disabled.
NOTE: On MZ models, the meter is powered by an independent internal power supply and will
most likely remain lit after a failure. Visual inspection of the front panel VDC ON/
ALARM indicator and/or monitoring of the alarm signals is required to detect a failure.If
the ALARM indicator is enabled to light red, the VDC ON/ALARM indicator must be
powered from the HSF output (see PAR. 3.4.3).
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 signals ±PF (PAR. 3.8.2.2). The ±PF logic level alarm option
must be used if the power supply is intended to operate below the minimum voltages listed in
Table 4.
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-
tions 5 and 6 of the DIP switches as shown in Figure 10A selects this option. The NC (pin 6 of the
rack adapter I/O connector) and NO (pin 7) signals are referenced to Alarm common (pin 14).
