Clary SP170-PDA - Manual (Page 7)

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A Clary Model PDA24 DC power supply is installed into the unit. This module slides in
from the front of the unit. It is secured by one 6-32 x 3/8 sems screw. The PDA24 supplies
24VDC to the Rear Panel of the unit. The Front of the PDA24 has two fuses, F1 (3A, 125V) which
protects the input of the DC power supply, and F2 (7A, 125V) which protects the output of the
PDA24 from accidental overloading. There is also test points on the front of the PDA24 which
allows you to measure the DC voltage being produced by the PDA24.
+24VDC Output………TB4 +24
+24VDC Output………TB4 +24
DC Ground……………TB4 GND
DC Ground……………TB4 GND
1.2.2 UPS Module (UPS)
Clary’s UPS Module provides critical loads with continuous, conditioned, regulated,
sinusoidal waveform power that is free from disturbances such as spikes, surges, brownouts or
blackouts. There are three models of the UPS Module available depending on your power
requirements. There is a 1250VA (875W), a 1250VA PLUS (875W, 1400W for 10 sec.) and a
2000VA (1400W) available.
Removal and Replacement (R&R) of the UPS module is quick and easy even with traffic
control devices (TCD’s) connected. R&R of the UPS module (for upgrades or in the rare event of
UPS failure) can be done without powering down the cabinet or otherwise affecting cabinet
operation in any way. Just switch the Bypass Switch on the front panel of the SP170-PDA to the
Bypass position and you are ready to pull out the UPS module.
Backup power is achieved with a set of rechargeable, SVRLA (sealed valve-regulated lead-acid),
maintenance-free, AGM (absorbed glass mat), batteries. The UPS module is controlled by an
onboard digital microprocessor at all times.
There are two basic modes of operation:
• Offline (Standby Operating Mode)
• Online (Continuous Operating Mode)
In both modes, the UPS continuously generates 120V AC power. The selected mode determines
when and how the UPS generated power is applied to the loads in the traffic cabinet.
Standby Operating Mode (OFFLINE):
During Standby operation, utility (AC) power enters the PDA module, goes through the MCB,
then into the UPS Module(if Bypass switch is switched to UPS) and passes through a normally
closed relay, then back out to the PDA module. This utility power is used to power the
intersection until a power disturbance occurs at which time, the relay is switched, routing the UPS
generated AC power to the PDA module which powers the cabinet. Typically, the UPS will then be