Section 6 Component Testing And Adjustment; Theory Of Operation, 1-Phase Generator Sets With Power Boost Iiie Voltage Regulator; Generator Troubleshooting - Kohler 8.5RMY Service Manual

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Operation and installation manual (52 pages)

Table Of Contents

Table of Contents

6.1 Theory of Operation, 1-Phase

Generator Sets with Power

Boost IIIE Voltage Regulator

Single-phase 8.5/11RMY generator sets utilize a

rotating-field alternator to produce AC current. Upon

activation of the generator master switch, DC current

from the battery magnetizes the rotor (field). When the

magnetized rotor rotates within the stator windings, an

electrical current develops within the stator. As engine

speed and generator output increase, the voltage

regulator feeds rectified stator output current to the rotor

through the brushes/slip rings to increase the strength of

the rotor field. As the rotor field increases in strength,

generator output also increases. The Power Boostt

IIIE voltage regulator monitors the generator output

voltage through leads 33 and 44 and allows the DC

current to flow to the rotor to meet load requirements.

See Figure 6-1.

6.2 Generator Troubleshooting

To determine the cause of no or low AC output, refer to

the troubleshooting flow chart in Figure 6-2. Before

beginning the test procedures, read all safety

precautions at the beginning of this manual. Many of the

test procedures include additional safety precautions.

Check the condition of the voltage regulator's 10-amp

fuse before performing the separate excitation

procedure. See Figure 4-2 or Figure 4-3 for the fuse

location. If the fuse is not blown, use the following

procedure to separately excite the generator using an

external voltage source (a 12-volt automotive battery).

Separately exciting the generator can determine the

presence of a faulty voltage regulator or reveal a running

fault in the rotor and/or stator. An external power source

duplicates the role of the voltage regulator and excites

the generator field (rotor). A generator component that

appears to be in good condition while stationary may

exhibit a running open or short circuit while moving.

Centrifugal forces acting on the windings during rotation

cause a broken circuit to open, or increasing

temperatures cause the insulation to break down,

resulting in a running fault. If this test shows that the

rotor and stator are in good condition, test the voltage

regulator using the tests in Section 6.3.

TP-5867 11/02