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Glossary of Terms GEH-6632 EX2100 User’s Guide
Modbus
A serial communication protocol developed by Modicon for use between PLCs and
other computers.
multiple bridges
Several power producing bridges operate in parallel to produce a high field current.
These share the exciter current load to provide redundancy and increased reliability.
NEMA
National Electrical Manufacturers Association; a U.S. standards organization.
non-volatile
Memory specially designed to store information even when the power is off, for
example Flash memory.
OLR
On-Line Repair, capability provided by redundant control elements.
over-excitation limiter (OEL)
OEL software limits the excitation current to prevent overfluxing the generator
power conversion module (PCM)
The PCM or Bridge consists of six three-phase rectifiers, with associated protection
and control devices, to generate the dc field current.
power current transformer (PCT)
A PCT can be attached to the generator line to provide a portion of the three-phase
power for the exciter, part of a compound source.
power distribution module (EPDM)
The PDM distributes 125 V dc to the power supplies for the controllers and I/O
termination boards.
power potential transformer (PPT)
A PPT is attached to the generator terminals to provide three-phase power for the
exciter; referred to as a potential source.
power system stabilizer (PSS)
PSS software produces a damping torque on the ge nerator to reduce generator
oscillations.