AMETEK BPS Series - Manual (Page 109)

User Manual AMETEK Programmable Power
BPS Series 109
6.2 Overall Description
Three-phase input power is routed from the back of the cabinet to a fuse holder terminal block located in
the bottom front of the unit. The lower front access panel has to be removed to gain access to the AC input
connection fuse block. From the fuse block, the AC input is connected to the three-phase input transformer
primary. The input transformer provides the required isolation between input and output of the BPS and
accommodates various input voltage 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
located in the middle of the BPS 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 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 is AC. This is set by the CPU controller based on this models features. 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 located in the top compartment of the BPS 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 BPS. This circuit breaker
functions as the main power on/off switch of the BPS 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 BPS 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 RS.
The individual assemblies are described in more detail in the following paragraphs. Refer to Figure 6-1
for an overall functional block diagram.