User Manual – Rev BE AMETEK Programmable Power
MX Series 189
ranges by employing multiple taps. Three sets of three-phase output
secondaries are provided by the transformer to produce three 140 VAC
unregulated output AC buses. Each of these outputs is fed into one of the power
modules. (A, B and C) The power modules can be individually removed although
for most configurations, all three are required. The power modules are in the
middle of the MX chassis and can be pulled out from the front after removing
the top access panel and disconnecting the power input and output wiring.
Each power module contains a three-phase PFC power input module. The PFC
module acts as a boost converter using a PWM converter topology to generate a
450 VDC regulated bus. A bank of high-capacity electrolytic capacitors for each
DC bus ensures ride through capability during brownouts and high current
demands.
The DC bus provides power to the AC amplifier. Each amplifier in turn consists
of four amplifier modules labeled #1 (A1, A2) and #2 (A1, A2). These four
amplifier modules are identical and interchangeable but all four must always be
present.
The output of the amplifier can be either AC, DC or a combination of AC and DC.
The mode is controlled by the CPU controller based on user selection. All four
amplifier modules within each power module are controlled by a single
Modulator board. The modulator board contains a high frequency PWM
modulator and additional control circuitry.
The CPU controller / oscillator assembly generates the reference waveforms and
provides frequency, amplitude, and impedance control. A current and voltage
sense board is located at the left bottom of the unit and is used to sense all
output current and voltage for both control and measurement purposes. The
current sensor board, in conjunction with the CPU controller, also supports the
programmable RMS current limit function.
The system interface board controls all interaction between controller, power
modules and current sensor board. The system interface board is in the top
compartment of the MX along with the controller.
Low voltage Power to the controller, amplifiers, system interface board and
sensor board is provided by a separate Low Voltage DC supply (LV Supply). This
LV Supply takes three-phase AC input directly from the AC input line through
circuit breaker CB1 located on the front on the MX. This circuit breaker functions
as the main power on/off switch of the MX unit.
The LV Power Supply board converts the AC input into several isolated low
voltage regulated DC supplies that are distributed throughout the MX chassis.
The LV power supply also supplies coil power for all contactors, including the AC
mains contactor (K2). A small fan is located near the LV Supply to provide
sufficient cooling of the supply and the other modules in the top section of the
MX.
The individual assemblies are described in more detail in the following
paragraphs. Refer to Figure 5-1 for an overall functional block diagram.
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