System Description
Ctrl Nr: PM375118-004
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1
System Description
This manual describes installation and operation of the PDI® WaveStar® Static Transfer Switch 2000 Amperes 3-
Pole (STS 2000A). The Static Transfer Switch (STS) is a three-pole, two-position transfer device that
transparently transfers, automatically or manually, an output load between two three-phase input power sources.
1.1
Basic Characteristics
Purpose
The purpose of the STS is to keep power supplied to a downstream mission-critical load by switching
between redundant power sources.
While a site UPS removes power anomalies originating between the power station and the site, the STS mitigates
the effects of anomalies between the Uninterruptible Power Supply (UPS), utility power source, or other source
and the STS load. These anomalies include:
•
Loss of an upstream utility or UPS source
•
Out of specification power from a power source
•
Faulty transformers in PDUs
•
Circuit breaker nuisance tripping
Transfer Switch
The STS 2000A is a standalone transfer switch with two AC input sources and one AC output
load. The STS transparently transfers the output load automatically from one power source to the other, if the
active source fails or goes out of specification, or manually by operator directive, for testing or maintenance.
Static Transfer Switch
Unlike electromechanical transfer switches, a static transfer switch has no moving parts.
It uses semiconductor technology, specifically silicon controlled rectifiers (SCRs), as power switching elements,
achieving faster transfers.
Sources
The two input AC power sources should be independent power sources that are nominally of the same
voltage, phase rotation, and frequency. Inputs are usually from uninterruptible power supplies (UPSs), but can be
utility power sources, transformer outputs, or PDU outputs.
Output load
The STS has a single AC output that supplies redundant power to downstream loads.
3-pole
The STS switches a 3-phase AC load between the two AC sources. The neutral wire is not switched.
1.2
System Layout
Figures 1, 2, and 4 show the layout of the STS 2000A.
Figure 3 shows operator interfaces.
Figure 5 has the 1-line electrical drawing.
