Clary SP Series-Model PD - Manual (Page 6)

T H E C O N T I N U O U S P O W E R C O M P A N Y
6
1.2 Operating Modes
Clary’s PD Series Uninterruptible Power Systems (UPS) are designed for powering low power
(i.e., LED & NEON) traffic & pedestrian indications, plus critical traffic control devices (i.e.,
controllers, modems, CMU’s, etc.). The power system consists of three elements, which work
together to provide critical loads with continuous, conditioned, regulated, sinusoidal waveform
power that is free from disturbances such as spikes, surges, brownouts or blackouts. These
elements are the:
1. UPS Module – (UPS)
2. Bypass Box
3. Battery Module
Backup power is achieved with a set of rechargeable, SVRLA (sealed valve-regulated lead-acid),
maintenance-free, AGM (absorbed glass mat), batteries. The complete UPS system 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 Bypass Box then into the UPS (if Bypass
Box is switched to UPS) and passes through a normally closed relay, then directly out to the
cabinet power bus, PDA, etc. 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 cabinet power bus. Typically, the UPS will then be drawing its power from the battery pack.
This operation continues until good utility power is restored, after which, the relays switch back to
route the utility power to the loads.
With Standby operation, 0.5 seconds (user programmable from 30ms to 2.5sec) after an outage is
detected, standby power is connected to the system and if desired, the Flash Command is
initiated, forcing the cabinet into Flash Mode operation. Depending on the size of the battery
system being used and the loading on the power system, backup power can continue for several
hours. NOTE: If the flash mode operation is not desired, make sure intersection load is not over
875 watts.