Rockwell Automation SF3000 Parallel Gate Amplifier System - Manual (Page 23)

About the PGA Module 4-1
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About the PGA Module
The PGA module isolates and amplifies the gate signal pulses received from one of
the two rack backplane channels, A or B. The type of PGA module used depends
upon the channel it will access. An Output-A PGA module (B/M O-60056) receives its
signals from channel A. An Output-B PGA module (B/M O-60071) receives its signals
from channel B. The user must ensure that the correct type of PGA module is used for
the channel desired.
Except for the interface to the rack backplane channels, the two PGA modules are
mechanically and electrically identical, as described in the following sections.
4.1 PGA Module Mechanical Description
The PGA module is a printed circuit board assembly that plugs into slot 3 or 4 (four-
slot PGA rack) or slot 3 to 8 (eight-slot PGA rack). One or two modules can be used in
a four-slot rack. Up to six modules can be used in an eight-slot rack. The two types of
modules can be combined in any desired configuration.
Each module consists of a printed circuit board and a faceplate. The top of the
faceplate is labeled "OUTPUT-A" or "OUTPUT-B," to indicate which set of backplane
signals the module will accept. Thumbscrews at the top and bottom of the faceplate
secure the module in the rack. The back of the module plugs into the rack backplane.
The faceplate contains a green "OK" LED indicator and four fifteen-pin female D-shell
connectors. The LED lights to indicate that the +5 VDC supply is present and the
module is functioning normally. The four fifteen-pin D-shell connectors are used to
output the amplified forward or reverse gate signals from the PGA module to the gate
coupling circuits in the Power Modules.
4.2 PGA Module Electrical Description
The PGA module will input the gate signals from its designated channel (A or B) on
the rack backplane. The channel carries the forward or the reverse gate pulses,
depending upon the connection between the DC Power Technology module and the
PGA Power Supply module, as described in chapter 3.
Other than channel selection, both types of PGA module operate identically. The
incoming gate pulses from the six inputs on each channel are optically isolated from
their respective biasing networks and FET gate firing circuits, and physically isolated
from the remaining circuitry on the Power Supply module, backplane, and PGA
module.
Each of the PGA module’s six FET outputs has a fan-out of four, providing each
module with the capability of driving up to four power bridges. A maximum of six PGA
modules can be used in the system. If all six PGA modules are used, a total of 24
power bridges (6 x 4) can be driven. Figure 4.1 shows one of the four gate signal
outputs.