Generac Power Systems 7 kW NG Repair Manual page 52

Section 2.4
Diagnostic Tests
PIN 5
5 4 3 2 1
9 8 7 6
14 13 12 11 10
PIN 14
J5 CONNECTOR
HARNESS SIDE
Figure 49. 10-20kW Fixed Excitation Test
Procedure: Rotor Amp Draw
1. Disengage the MIN/MAX feature and manual scale on the VOM.
2. Set VOM to measure DC amperage.
Note: Consult the meters documentation for proper setup
procedure. See Section 1.4 "Measuring Current" for fur-
ther information.
3. Connect the black (negative) meter test lead to Pin 13-J5
and the red (positive) test lead to the positive battery
terminal. See Figure 50.
4. Measure and record the static rotor amp draw.
5. Set AUTO-OFF-MANUAL switch to the MANUAL position.
6. Measure and record the running rotor amp draw.
7. Acknowledge and reset the "under-voltage" present on the
J5 CONNECTOR
HARNESS SIDE
5 4 3 2 1
9 8 7 6
14 13 12 11 10
PIN 13
0
11.83Ω
ROTOR
4
FIELD BOOST DIODE
56
Page 50
63 VAC
Results
1.
Note: To calculate rotor amp draw take the battery voltage
applied, divided by the actual resistance reading of the
rotor. Rotor resistance can be measured between Pin 13
J5 and Pin 12 J5.
Example
Model
Wires 2 and 6 Voltage
Wires 11 and 22 Voltage
Static Rotor Amp Draw
Running Rotor Amp Draw
These results match Column B in the chart. Refer back to
Problem 1 and follow letter "B"
1.09 DC
Amps
RED
J5 PIN 12
J5 PIN 13
1.09 DC
Amps
VOM METER
Figure 51. Rotor Amp Draw Test
PART 2
controller; leave AUTO-OFF-MANUAL switch in the OFF
position.
Using the values recorded in the above procedure,
compare the results to Table 10 "Results – Fixed
Excitation Test/Rotor Amp Draw Test". Determine the
appropriate lettered column to use and refer back to the
flow chart. The rotor amp draws area calculated amp
draw and actual amperage readings may vary depending
on the resistance of the rotor.
12.9VDC
12.3 Ohms x 1.05 DC Amps
Figure 50.
POSITIVE BATTERY
TERMINAL
12.9 VDC
AC GENERATORS
17kW
53 VAC
31 VAC
1.09 Amp
1.10 Amp
+ -
BATTERY
12.9 VDC
1.09 A
11.83Ω
OHM'S LAW