Operating instructions

16 Power and Control Wiring
Figure 4 Typical One-Line Diagram of Two PDUs and a Static Transfer Switch
5.4 Control Wiring Connections
No control wiring is needed on the standard STS2. Only certain options require external control
wiring. See 6.0 - Options on page 18 for details
5.5 Remote Source Selection Wiring
An optional Remote Source Selection board may be installed in your STS2. This board is installed
in the same bay as the communications options. See Figure 21 on page 39 and Figure 22 on
page 40 for the location of these options. See Figure 23 on page 41 for information on the control
wiring for the Remote Source Selection option.
The Remote Source Selection allows you choose the preferred input source from a remote location.
Terminal connections allow the customer to remotely select a source to be the preferred source in
the same process as the local source transfer selection.
The unit’s preferred source selection and Remote Source Selection are active at the same time, with
the STS2 following the last request for a preferred source change, regardless of whether it was from
the local or Remote Source Selection controls.
A six pin terminal block provides the Remote Source Selection connections. Two pairs of wires are
used from the switch to trigger the source selection. You can select the type of switch used for this
remote control. Connections are made to four of the connections, using Form A dry contacts. The
contacts are numbered left to right:
CB5
STS1 STS2
CB1 CB2
CB3CB4
K1
K2
K3K2 K3K1
225A 225A225A 225A 225A225A
ISOLATION
TRANSFORMER
SOURCE 2
MICB2
SOURCE 1
ISOLATION
TRANSFORMER
MICB1
SS1 SS2