Elgar SmartWave SW1750A, Operation Manual

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SW 5250A•SW 3500A•SW 1750A Installation
Operation Manual 2-15
The output power and sense leads should be shielded and the shield connected to the
chassis to prevent noise pickup (or radiation to sensitive circuits in the vicinity). Again,
the shield should be connected to chassis ground.
Due to the high voltages present, 312 VRMS line-to-neutral and 437 VRMS line-to-line
cables rated to these voltages must be used for both the Power and Sense leads.
2.9.2
2.9.3
2.10
SW 3500A and SW 1750A Output Connections
The Model SW 3500A has phase A and phase B present; phase C is an open circuit.
Make connections as for the SW 5250A but with phase C missing.
The Model SW 1750A has only phase A present; phases B and C are open circuits.
Wiring of Unit
Due to the high voltages and frequencies involved, it is recommended that all input and
output wiring is protected with flexible conduit. Holes for this purpose are made in the
terminal box (see Figure 2–2). All wiring must meet local standards for safety.
Wire Gauge Selection
The following guidelines assist in determining the optimum cable specification for
your power applications. These guidelines are equally applicable to both DC and low
frequency AC (up to 450 Hz) power cabling. The same engineering rules apply whether
going into or out of an electrical device. Thus, this guide applies equally to the input
cable and output cable for this Elgar instrument and application loads.
Power cables must be able to safely carry maximum load current without overheating or
causing insulation destruction. It is important to everyday performance to minimize IR
(voltage drop) loss within the cable. These losses have a direct effect on the quality of
power delivered to and from instruments and corresponding loads.
When specifying wire gauge, the operating temperature needs to be considered. Wire
gauge current capability and insulation performance drops with the increased
temperature developed within a cable bundle and with increased environmental
temperature. Thus, short cables with generously derated gauge and insulation
properties are recommended for power source applications.
Avoid using published commercial utility wiring codes. These codes are designed for
the internal wiring of homes and buildings and accommodate the safety factors of wiring
loss, heat, breakdown insulation, aging, etc. However, these codes consider that up to
5% voltage drop is acceptable.