8.
105. AC Connections
CAUTION:
A)
All
VST
inverter system units contain hazardous AC and DC voltages. Because of these voltages,
a qualified electrician must install the
VST
inverter system, AC line service, and batteries. The
electrician must install the AC line service according to local, state and NEC codes and must be
familiar with batteries and battery installation.
B)
Before installing, maintaining, or servicing the unit, always remove or shut off all sources of AC
and DC power to the
VST
inverter system. Turn off the AC line input circuit breaker at the service
panel and place the
VST
Battery Switch S2
in the
OFF
position to make sure the unit will not
supply output voltage.
C)
Whenever AC and/or DC voltage is applied, there will be AC voltage inside the
VST
inverter sys-
tem unit; the unit can supply power from AC line or from its batteries. To avoid equipment damage
or personal injury, always assume that there may be voltage inside the
VST
inverter system.
D)
Remove rings, watches, and other jewelry before installing the AC wiring. Always wear protec-tive
clothing and eye protection and use insulated tools when working near batteries. Whenever
servicing an energized unit with the inside panel open, electric shock is possible; follow all local
safety codes.
TEST BEFORE TOUCHING!
E)
To reduce the risk of fire or electric shock, install the
VST
inverter system and the batteries in a
temperature-controlled and humidity-controlled indoor area free of conductive contaminants. See
Section 103
for operating environment specifications.
105.1 AC Wiring Preparations
1.
Remove the system’s front cover. Make sure the
VST
Battery Switch S2
is in the
OFF
position.
2.
Make sure the
VST
inverter system input and output voltages are correct for the particular applica-
tion. Remember that the
VST
system provides single-phase power only.
3.
The input circuit breaker in the input service panel provides the means for disconnecting AC to
the
VST
inverter system. Only authorized persons shall be able to disconnect AC to the unit. (See
N
EC 700-20 and 700-21
.)
CAUTION: To prevent electrical shock or equipment damage, for all units, the
VST
Battery
Switch S2 and the AC input circuit breaker at the service panel are all OFF before making
AC connections to the
VST
inverter system.
4.
If not previously done, remove cabinet knockouts for AC Input and AC Output as described in
Sec-tions 104-4, 104.5 or 104.6
depending on mounting method
CAUTION: Do not drill the cabinet; drill filings may damage the unit and prevent it from
operating. If larger knockouts are needed, use a chassis punch to enlarge the appropriate
knockout. Do not add additional or unnecessary knockouts.
5.
Install the input and output conduits.
6.
Run the AC Input service conductors and AC Output conductors through separate conduits.
VST
inverter system emergency output circuits shall be installed in dedicated conduit systems and not
shared with other electrical circuits as described in
NEC 700-9(b)
.
105.2 AC Input and AC Output Connections
CAUTION: Prior to making any wiring connections to unit make sure branch AC input circuit
breaker feeding the
VST
unit is turned off at the service panel!
The
VST
models can be configured for various modes of operation and are described in this section. Re-
fer to the appropriate wiring diagrams to properly connect the utility AC power, fixtures and external
switch-ing device (where applicable). Perform all wiring procedures in accordance with applicable codes.