Kohler COM7.5, Service Manual

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TP-6120 5/02 1 Section 1 Specifications
Section 1 Specifications
1.1 System Description
The COM7.5 generator set provides reliable backup DC
power to cable TV systems or telecommunication sites
in place of, or in addition to, batteries. The COM7.5 is
available in 48 and 96 VDC models. The generator set
nameplate indicates the unit’s rated voltage.
The system batteries provide power at 48 or 96 volts.
When power fails, the control system signals the
generator set to start. The generator set provides DC
power for continued or reserve operation of the system.
The COM7.5 generator set has both local and remote
control capabilities. The unit runs on natural gas or LP
vapor.
1.2 Generator Set Functional
Description
The COM7.5 generator set system consists of the
generator set (engine and generator) and the control
system.
The generator set provides regulated DC
voltage to the telecommunications power system. The
control system provides complete control of the engine
and generator, accepts remote control commands, and
delivers local and remote annunciation of unit status.
Internal control functions include start and stop logic,
fault monitoring, unit voltage control, engine speed
(rpm) governing, and a local LED for fault annunciation.
Under very light loads, the generator set operates at low
speed. As loads increase, the control system maintains
constant generator output voltage by increasing the
generator set engine speed.
The Kohler CH20 engine drives a direct-connected,
variable-speed, 3-phase, voltage-specific generator to
produce high-frequency AC power.
A 3-phase,
full-wave rectifier in the control system rectifies the
output to produce low-ripple, unfiltered DC power.
1.3 Specifications
Figure 1-1, Figure 1-2, and Figure 1-3 contain
generator set, alternator, and engine specifications.
Refer to the scheduled maintenance section for service
details.
Generator Set Specification 48 VDC 96V
Manufacturer Kohler
Dimensions,
L x W x H, mm (in.)
613 x 413 x 55
(24.1 x 16.3 x 21.8)
Weight, dry, lb. 200
Rated kW* 7.5
Rated voltage (after rectifier) 52 104
Rated amps 144 72
* Derate approximately 4% per 300 m (1000 ft.) over 153 m
(500 ft.) above sea level. Derate 1% for each 5.5
°
C (10
°
F)
increase in temperature above 25
°
C (77
°
F).
Figure 1-1 Generator Set Specifications
Alternator Specification 48 VDC 96 V
Stator resistance, ohms 0.024 0.054
Stator type 3-Phase, 3-Lead, Ungrounded
Excitation method (rotor) Permanent-Magnet, Brushless
Coupling type Direct-to-Engine
Insulation (stator) Class 155, Epoxy Varnish,
Vacuum-Impregnated
Winding material Copper
Figure 1-2 Alternator Specifications