Clary SP170-PDA - Manual (Page 6)

6
1.2 Operating Modes
The SP170-PDA is basically made up of two parts, the Power Distribution Assembly and the
UPS module.
1.2.1 Power Distribution Assembly (PDA)
The Power Distribution Assembly (PDA) is responsible for the input power and provides a
30 Amp Main Circuit Breaker (MCB). The MCB supplies power to the UPS/Cabinet and controller
receptacles, the Flasher Bus Circuit Breakers and the Mercury Contactor (MC). The MC is a
normally closed mercury contactor rated at 50 Amps.
The Flash Bus Circuit Breakers are rated at 20 Amps and feed the two Model 204 Flasher
Units that provide four alternating signal drives rated at a maximum of 10 Amps each. These are
wired as followed to the Terminal Blocks on the rear of the unit:
FCB1-CKT#1……..T2-2
FCB1-CKT#2……..T2-3
FCB2-CKT#1……..T2-4
FCB2-CKT#2……..T2-5
The MC provides power to six 5 Amp circuit breakers. These signal circuit breakers are
wired to the Terminal blocks on the rear panel of the PDA which then can be wired to the Output
File Assembly. These are wired as followed to the Terminal Blocks on the rear of the unit:
SB1……..T2-7
SB2……..T2-8
SB3……..T2-9
SB4……..T2-10
SB5……..T1-4
SB6……..T1-8
The Signal Circuit Breakers (SCB) are equipped with indicating switches. These switches
are wired in parallel, and closed when a breaker is tripped, or set in the OFF position. Common
input to the switches is attached to the load side of the MCB. The normally closed contact of the
switches is wired in common to the MC coil and Flash Transfer Relay Coils (FTR). When any or
all of the Signal Bus Circuit Breakers trip, or are set to the OFF position, the indicating switches
supply power to the MC coil and the FTR relays which will cause the cabinet to go into a flashing
condition. At this time, the Flash indicator will remain in the solid ON state.
Two Flasher units are installed in this assembly, and they receive power from a two pole
20 Amp Breaker attached to the load side of the MCB.
A Ground Fault power source is provided on the front and rear of the unit. A GFI
receptacle is provided on the front panel of the unit. On the rear, TB1-10 is wired to the Load side
of the GFI receptacle.