HSF (M) 300W 042315
13
3.8.2.2 OPTICALLY-COUPLED LOGICAL ALARM
The second option uses optically-coupled logic level alarm signals, +PF (pin 5 of the rack adapter
I/O connector) and -PF (pin 13), provided directly from the Kepco RKW power supply that is the
heart of the HSF. This option is selected by setting positions 5 and 6 of the DIP switches as shown
in Figure 10B. Use this option if the power supply will operate below the minimum voltages speci-
fied in Table 4.
FIGURE 10. DIP SWITCH SETTINGS FOR OPTICALLY COUPLED LOGICAL ALARM
The logic alarm circuit is a diode transistor optical coupler (see Figure 11). The transistor is nor-
mally conducting. When the alarm is activated upon detection of power loss, overvoltage, fan
fault, overtemperature or overcurrent condition, the transistor cuts off and the collector emitter cir-
cuit is open. Figure 12 is a timing diagram of the power fail signal.
The default state of the alarm is logic low. The sink current for the optocoupler is 50mA maximum,
the maximum collector to emitter saturation voltage is 0.40 Volts, and the collector to emitter volt-
age is 40 volts maximum. The PF signals are isolated from the AC input and DC output.
FIGURE 11. OUTPUT ALARM CIRCUIT OPTICALLY ISOLATED
3042878
5
5 +PF
+PF 5
5
SW1
-PF 6
6
SW2
6
6 -PF
OFF
ON
OFF
ON
USE N.O. AND N.C CONTACTS
(FACTORY DEFAULT)
OF INTERNAL RELAY
A
LOGICAL ALARM
USE OPTICALLY-COUPLED
B
(+PF AND -PF)
5
6
6
SW1
5
SW2
OFF
ON
ON
OFF
+PF 5
-PF 6
6 -PF
5 +PF
TAB
