TP-6953 7/19 123Section 7 Troubleshooting
7.6 Paralleling Troubleshooting—When Breaker Does Not Close to Bus
7.6.1 Faults Not Shown
Step Potential Cause
Explanation Troubleshooting
1 PGEN communication
not operational
The controller must have seen PGEN communication with at least one other
node at some time since the last power cycle event before it will close the
breaker.
In Controller Config - > Communication Setup, verify the PGEN Nodes Online
is at least 2. If so, continue troubleshooting at Step 8 otherwise, continue on
to Step 2.
2 Single generator
application
There is only one generator on site, but the controller is expecting to see PGEN
communication. The controller supports this scenario if the controller is
configured in Standalone mode. Standalone mode can be set using the
standalone input to the controller or in Kohler SiteTecht.
Configure a digital input to Standalone mode and assert it, or set
Standalone mode in Kohler SiteTecht. Note, Standalone mode should
only be asserted if there is only one generator set at the site.
3 PGEN wiring not
connected correctly
PGEN communicates over an RS-485 connection. RS-485 requires that the
network be connected in a daisy-chain configuration, terminated at 120 Ohms
at either end of the network and that positive (B) and negative (A) polarity be
maintained.
Verify wiring, all PGEN + connections should be connected with daisy-chain
wire (Belden #9841 or equivalent). Verify terminations are at the end of the
network. Verify that there are no unintentional or loose connections.
4 Baud rate
misconfigured
One of the controllers on the network is attempting to communicate at a
different baud rate than the other controllers. This results in collisions on the
communication bus and incorrect interpretation of the data.
In Controller Config - > Communication Setup, verify that the baud rate of all
generators on the network matches. Default is 57,600 baud.
5 Interference The PGEN network is seeing noise which makes it difficult for the generator
controllers to communicate.
Verify that PGEN network uses Belden #9841 or equivalent. Verify that the
shield drain for the cable is grounded at only one end.
6 Short circuit in
communication wiring
The RS-485 communication wires are short-circuited together. In Controller Config - > Communication Setup, verify the PGEN Node ID is
less than 16. If not, check the PGEN wiring for short circuits. Otherwise,
continue troubleshooting to Step 7.
7 Intermittent connection
in PGEN wiring
Although the generator controllers can occasionally communicate, the
connection is unreliable. This can be caused by a short or open circuit.
It is not uncommon for small c ommunications wire to not connect directly to
a terminal block well. Verify there are no loose wiring connections or
“whiskers” at the PGEN terminal blocks. “Fork”, “ring”, or “crow’s feet”
connectors are preferred for terminal block connections.
8 Unable to establish
first-on lock
The generator is trying to close to a dead bus but it is not receiving permission
from one of the other nodes to allow it to do so. This can occur if one of the
other nodes has seen a node removed from the network.
Cycle power on all generators.
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