Kohler 12EFKOZD, Installation Manual, Page: 70 / 84

TP-7045 3/18c 70 Section 9 Paralleling Generator Sets
9.6 Troubleshooting When Running in AUTO
9.6.1 Faults Shown
Step Potential Cause Explanation Troubleshooting
Fault: Generator Phase Rotation Mismatch
1 This generator is wired
with the opposite phase
rotation of all the other
generators on the
paralleling bus
The controller has validated that the bus
metering is accurate relative to this
generator, if the bus phase rotation is
backwards to the generator, the phase
rotation must really be different.
Verify wiring between this generator and
the paralleling breaker. It may be
necessary to reverse two phases between
the generator and the paralleling breaker
and then to reverse the sensing at the bus
to match. This generator should be started
and closed to a dead bus again to validate
the changes.
2 The wiring between the
paralleling breaker and
the paralleling bus is
incorrectly connected
(two phases are
reversed)
Voltage from other generators comes into
this generator as incorrect phase rotation
because the wiring connections to the
paralleling bus are reversed, even though
the rotation of the other generators is
identical to the rotation of this generator.
Verify wiring between the paralleling
breaker and the paralleling bus. It may be
necessary to reverse the connection of two
of the leads. This generator should be
started and closed to a dead bus again to
validate the changes.
3 The generator which is
connected to the
paralleling bus has the
opposite phase rotation
of this generator and all
others
Voltage from the other generator comes
into this generator as incorrect phase
rotation because the wiring connections
from the other generator to the paralleling
bus are reversed, even though the rotation
of the other generators is identical to the
rotation of this generator.
Verify wiring between the paralleling
breaker and the paralleling bus of the other
generator. It may be necessary to reverse
two phases between the paralleling breaker
and the paralleling bus on the other
generator. The other generator should be
started and closed to a dead bus again to
validate the changes.
Fault: Dead Bus Sensed When Live Bus Expected
1 The wiring was not
connected between the
load side of the
paralleling breaker for
this generator and the
paralleling bus
This generator controller observed
accurate bus voltage when it closed the
breaker, the other generator controller did
the same, but the bus of this generator is
not connected to the bus of the other
generator. The other generator is
energizing the load, this generator cannot
energize the load as there is a
disconnected wiring between this generator
and the paralleling bus.
Verify wiring between the paralleling
breaker and the paralleling bus of this
generator.
2 The wiring was not
connected between the
load side of the
paralleling breaker for
the other generator and
the paralleling bus
This generator controller observed
accurate bus voltage when it closed the
breaker, the other generator controller did
the same, but the bus of this generator is
not connected to the bus of the other
generator. The other generator is not
energizing the load because it is not
connected to it—this generator may be
able to energize the load, but there is no
simple way of telling this without
connecting the output of the other
generator.
Verify wiring between the paralleling
breaker and the paralleling bus of the other
generator.
Fault: Bus Voltage Out of Spec
1 The generators which
are connected to the
paralleling bus are
overloaded
When the generators which are supplying a
load are overloaded, their engine speed will
decrease, resulting in a decrease in output
voltage. Sometimes this decrease in output
voltage is sufficient to allow the generators
to recover.
Verify the load requirements are met by a
single generator. If not, it may be
necessary to connect several low priority
loads to load shed outputs from the
paralleling generators to avoid overloading
a single generator.
2 Excessive cable lengths
from generators to
paralleling bus
Although a single generator can handle the
load, the cables which connect the
generator to the paralleling bus are too
long or too small of gauge, resulting in
insufficient bus voltage.
Increase wire size on the generator
connection leads.