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1
Introduction
Alpha Technologies
1.4
Automatic Transfer Switch (ATS) System
1.4.1: Automatic Transfer Switch System Description
The ATS system automatically provides backup power to the loads. See Figure 1.4.1 for a
system block diagram. The ATS also allows for loads rated higher than the UPS can supply. The
ATS is the outlet for the UPS’s output power if line power is unqualified.
The ATS’s maximum input current is 40 Amps. Line power is connected to the ATS’s input
(Figure 1.4.2). When the line is qualified, it is sent to the loads.
When the line is unqualified, the UPS controller detects this and sends a signal via the control
line to the ATS, causing an internal contactor to transfer the load from the line to the UPS’s
output. Backup battery power is provided to the loads until the line is qualified or the batteries
are discharged.
For installation and start up instructions, see Sections 2.2 and 2.3.
Figure 1.4.1
Simplified Block Diagram for the Novus 1800TP System With Automatic Transfer Switch
Automatic Transfer Switch
(ATS)
Utility Line
(Line is Qualified)
Power
Upstream Circuit Breaker
Downstream Circuit Breaker
(If used)
Power From UPS
(Line is Unqualified)
UPS Line
Monitoring Circuit
Output
Power
Control
Line
Status/Self Test
Terminal Block
To Intersection Controller
Flash Control Point
Line Power Input
(40 Amps Maximum)
Output Power to Loads
Batteries
Novus 1800TP
(Backup power)
