User Manual

3Rack ATS AP44xx User Manual
Internal Protection Measures
ATS units may include the following internal protection measures:
• Input relays in every
model open when their
source is
disconnected to help
prevent electric
backfeed from one
input cord into another
(ATS 1).
• Two or four
non-replaceable fuses
(depending on the
model) help to protect
the ATS from short
circuits (ATS 2).
• Some 2U models have
circuit breakers to
help protect against
bank overload (ATS
3).
The rack ATS does not include power surge protection. To help protect your ATS from external power
surges, it is always recommended that you connect each ATS source to a Double Conversion On-Line
Uninterruptible Power Supply (UPS).
How Switching Works
1. You configure the ATS to accept power that meets the needs of your equipment by adjusting the
following settings (see “Configuration Tab” on page 83 for more details).
– Line VRMS: The ideal voltage for your equipment. Acceptable line voltages vary per ATS
model (see the specification sheet for your ATS model on www.apc.com).
– Transfer limits: The maximum and minimum voltages the ATS will accept before switching
sources. Transfer limits are meant to allow for small, acceptable surges and drops in power.
The ATS should not operate near the upper transfer limit for long periods of time.
– Transfer ranges: Pre-defined sets of transfer limits. You can configure up to three transfer
ranges, but you can enable only one transfer range at a time.
– Sensitivity: How long the ATS waits to determine whether or not it will switch sources.
High sensitivity provides extra responsiveness for delicate equipment. Low sensitivity helps to
prevent excessive switching in cases of fluctuating power inputs.
pdu0777a
Source A
Source B
Load
ATS 1
Source A
Source B
Load
ATS 2
Source A
Source B
Load
ATS 3
Attached
equipment
Attached
equipment
Attached
equipment