RELAY TABLE GROUP REPAIR INSTRUCTIONS
Section I. INTRODUCTION
a. Section I of this chapter includes a brief des-
cription of the assemblies that make up the relay ta-
ble group, overall functional operation, symptoms of
relay table group malfunction, and relay table group
b. Subsequent sections of this chapter include
repair instructions for the assemblies which are part
of the relay table group.
8-2. Relay Table Group Description.
a. The relay table and related parts (fig. 8-1)
intrudes the control relay assemblies, the excitation
assembly exciter and the load measuring unit. The
load measuring unit, and the excitation assembly
exciter are common to all modes and classes of sets.
Control relay assemblies include the tactical relay
assembly (used on all sets), precise relay assembly
(used on Mode 1, Class 1 sets), and two different
special relay box assemblies (one used on Mode I
sets and the other used on Mode II sets).
b. The tactical, precise, and special relay box
assemblies contain control relay modules for over-
voltage, short circuit, and reverse power on all
sets. Class 1 sets also contain additional control
relay modules for underfrequency, undervoltage, and
c. The excitation assembly exciter system pro-
vides control of excitation voltage to the main gener-
ator to produce voltage buildup in the generator field
The excitation system assembly contains a
voltage regulator that senses the generator output
voltage and uses it as a reference to control field
current in the generator and thus regulate the gener-
ator output voltage level.
d. The load measuring unit (LMU) is supplied on
all sets. The LMU provides a dc signal proportional
to the real power (kw) being delivered by the main
generator. Refer to paragraphs 7-1 and 7-2.
8-3. Relay Table Group Symptoms and Isolation of
Malfunctions in the relay table group will be electrical
in nature, and will affect the generator output voltage,
via the excitation system assembly, and normal sys-
tern operation due to a malfunctioning protection relay
in the tactical precise or set special relay box assem-
bly. If the set is in operable condition, the equip-
ment tests listed in table 8-1 can be performed to iso-
late the malfunction.
Section II. CONTROL RELAY ASSEMBLIES
This section includes repair instructions for the tac-
tical relay assembly, precise relay assembly, and
special relay box assemblies.
See figure 8-1, unscrew electrical connectors, and
remove the tactical relay assembly (2), precise re-
lay assembly (4), special relay assembly (14), ex-
citation assembly (18), and relay table (52), as re-
Tag all electrical connections removed
during disassembly for position identi-
fication during reassembly.
a. Tactical Relay Box Assembly.
(1) See figure 8-2 and disassemble the tactical
relay assembly as follows:
(a) Remove screws (1) and washers (1A) and
remove cover (2).
(b) Tag and disconnect all wiring harness
(c) Complete disassembly in accordance
with figure 8-2.
(2) See figure 8-3 and disassemble the tactical
relay resistor assembly.
b. Precise Relay Box Assembly (Class 1 Sets).
(1) On Class 1, Mode 1 Sets, see figure 8-4 to
disassemble the precise relay box assembly.
Tag and disconnect all electrical leads
prior to removal of wiring harness (7).
(2) See figure 8-5 for disassembly of the re-
Change 7 8-1