SECTION 4 OPERATION
88
4.6 OUTPUT VOLTAGE FORMS
The AMX-Series Power Source can be configured for various output voltage forms, depending
on the power source model.
A recommended strategy for selecting the optimum output voltage form is based on two basic
philosophies. The first is to use a direct-coupled output form whenever possible. The
second is to select the minimum voltage range necessary to drive the load.
Direct-coupled output is preferred because the output impedance is extremely low, also low
frequency limitations associated with transformer outputs do not exist. This is especially true
when attempting to perform sub-cycle transients.
Selecting the minimum voltage range necessary to drive the load allows the power source to
operate more efficiently and usually has more current available. This results in less heat
being dissipated into the surrounding environment.
Paragraph 4.6.1 discusses the various circuits associated with the different output forms.
4.6.1 SYSTEM ARCHITECTURE
AMX-Series Power Sources can be configured for single, split, and three phase output voltage
forms. Figure 4.6.1 is a simplified block diagram of the possible output architectures. Only
the direct-coupled output forms are shown. All of the forms can be supplied with
transformers to raise the output voltage level.
The 1 PHASE (FORM 1) mode of operation is a one vector output form. All of the power
amplifiers are connected in parallel to form one output vector. The standard, direct-coupled
version of this output form is capable of 0-135 VAC
l-n
(0-150 VAC
l-n
for the Models 112, 312,
and 125-AMX). The voltage ranges of the various transformer output forms are defined in
section 3.2.
The 2 PHASE (FORM 2) mode of operation is a two vector output form where the vectors are
separated by 180 and equal in amplitude. This output form uses power amplifiers in pairs,
one for each vector. The load can be attached from either line to neutral, line to line, or a
combination of both (line to line only in the case of the Model 125-AMX). The standard,
direct-coupled version of this output form has a voltage range of 0-270 VAC
l-l
(0-300 VAC
l-l
for
the Models 112, 312, and 125-AMX). The voltage ranges of the various transformer output
forms are twice the 1 PHASE voltage. Models 305, 308, 320, 330, 345, 360, 390 and
3120-AMX, only two of the three power amplifiers are connected--limiting these systems to
producing only two-thirds of rated output power.
NOTE: The AMX-Series Power Sources do not support voltages in excess of 600 VAC
rms
due
to controller, safety, and spacing limitations. Attempting to defeat the inherent programming
limitations of the controller to obtain higher voltages is strongly recommended against.
The 3 PHASE (FORM 3) mode of operation is a three vector output form with vectors
normally separated by 120. Power amplifiers are supplied in groups of three with this output
form and are WYE connected. A WYE load is connected to the A, B, C, and Neutral
terminals of the output terminal block. This output form will also drive DELTA loads.
DELTA loads are simply connected to the A, B, and C terminals of the output terminal block
with the Neutral terminal not connected. The standard, direct-coupled version of this form
has an output voltage range of 0 to 135/234 VAC (0 to 150/260 VAC for the Model 312-AMX).
The line to neutral voltage ranges of the various transformer output forms are the same as the
1 PHASE voltage.
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