Ametek California Instruments MX15 Series User Manual page 104

of high capacity electrolytic capacitors for each DC bus ensures ride through capability during
brown-outs 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 (looking from the rear) 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 located in the top compartment of the MX15
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
MX15. This circuit breaker functions as the main power on/off switch of the MX15 unit.
The LV Power Supply board converts the AC input into a number of isolated low voltage
regulated DC supplies that are distributed throughout the MX15 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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