Table of Contents
Advertisement
TW 3700 • TW 5550
2 .9 .2
T W 3 7 0 0 OU T P U T CONNE CT I ONS
The Model TW 3700 has phase A and phase B present; phase C is an open circuit.
Make connections as for the TW 5550 but with phase C missing.
2 .1 0
WI R I NG OF U NI T
2 .1 0 .1
WI R E GAU GE S E L E CT I ON
Due to the high voltages and frequencies involved, it is recommended that all input and
output wiring be 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.
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. Such a loss directly detracts from the quality
performance specifications of this Elgar instrument. Frequently, these codes do not
consider bundles of wire within a cable arrangement.
In high performance applications, as in motor start-up and associated inrush/ transient
currents, additional consideration is required. The cable wire gauge must consider
peak voltages and currents that may be up to ten times the average values. An
underrated wire gauge adds losses that alter the inrush characteristics of the
application and thus the expected performance.
Elgar TrueWave
Installation
2-13
Advertisement
Table of Contents
