Securitron iEXD-24 - Manual (Page 12)

PN# 500-18900
Page 12
Rev. D, 10/07
6.1 POWER SUPPLY CONNECTIONS
Figure 6 shows power supply connections for Securitron's 1 Amp units and larger supplies.
Either supply must first be connected to a source of 115 VAC. 2 wires then carry DC power to
the unit (see figures 2 and 3). In the case of the larger, multiple output supplies, the number of
doors powered should be spread among the "P" terminals. “Medium” sized supplies employ the
CCS-4 control board with four “P” terminals and the largest supplies employ the CCS-8 control
board with eight “P” terminals.
Each “P” terminal conducts power through a 2.5 Amp Polyswitch. This is a special type of
automatic fuse. If one of the Polyswitches receives an overload, it will rapidly cut the current
down to a small leakage current (about 100 mA) which will allow the rest of the doors to
continue to operate. Note that each “P” output includes a slide switch and LED. The slide switch
can cut DC power to its respective output and the LED monitors when the output is powered. In
the event of one of the Polyswitches tripping, the associated LED will go out and there is a reset
procedure. First, correct the overload condition. Next, all current must be removed
from the Polyswitch for a period of 10 seconds. You do this by simply moving the
associated slide switch to the “off” position. Then, return the slide switch to “on” and operation
will return to normal. If you haven’t corrected the overload, naturally the Polyswitch will trip
again but you must always de-power and re-power the Polyswitch to reset it.
If your power supply includes a battery pack, the Polyswitch will always trip as described in
the previous paragraph. If, however, you are not employing batteries and you are using a
Securitron power supply larger than one Amp in capacity, a short circuit or overload may not trip
an individual Polyswitch. This is because the power supply itself is internally short circuit
protected for additional safety and the supply itself may completely shut down before the
individual Polyswitch on the affected zone can trip. The issue of whether the power supply
shuts itself off or an individual Polyswitch trips depends on the overload current. In
the case of a dead short, the overload current is very high and the power supply will shut down
first. An overload greater than 2.5 Amps but less than the total capacity of the supply will rather
cause the zone Polyswitch to trip. The presence of a battery always trips the Polyswitch because
the battery will supply high current into any short or overload once the power supply can no
longer maintain its voltage.
It’s simple to determine whether an individual Polyswitch has tripped or whether the power
supply has shut down by looking at the individual zone LED’s. One will be off in the event of an
individual Polyswitch trip and they will all be off in the event of power supply shut down. To
recover from power supply shut down, you have to identify and correct the overload or short
circuit. This should be done by turning off each zone slide switch until you find the one that
restores normal operation of the supply by correcting the overload. You should then deal with
the actual cause of the overload in the downstream wiring.