CUMMINS OT III Operator's Manual

OT III

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by any means, is strictly prohibited.

Transfer Switch
40 to 1000 Amperes
Nonautomatic/Remote

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by any means, is strictly prohibited.

SECTION TITLE PAGE

1INTRODUCTION 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Operator’s Manual1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transfer Switch Application 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Model Identification 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

How to Obtain Service1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2DESCRIPTION 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cabinet2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transfer Switch 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

3OPERATION 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Local Operation 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Remote Operation 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Manual Operation 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Preventive Maintenance3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4TROUBLESHOOTING 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Transfer Switch Does Not Transfer to the Standby Source4-1. . . . . . . . . . . . . . . . . . . . .

Transfer Switch Does Not Retransfer to the Normal Source4-1. . . . . . . . . . . . . . . . . . . .

INCORRECT SERVICE OR REPLACEMENT OF PARTS CAN RESULT IN
DEATH, SEVERE PERSONAL INJURY, AND/OR EQUIPMENT DAMAGE.
SERVICE PERSONNEL MUST BE QUALIFIED TO PERFORM ELECTRICAL
AND/OR MECHANICAL SERVICE.

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by any means, is strictly prohibited.

This manual includes the following symbols to indi-
cate potentially dangerous conditions. Read the

manual carefully and know when these conditions
exist. Then take the necessary steps to protect per-
sonnel and the equipment.

This symbol warns of immediate
hazards that will result in severe personal injury
or death.

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unsafe practice that can result in severe per-
sonal injury or death.

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safe practice that can result in personal injury
or product or property damage.

High voltage in OT transfer switch components pre-
sents serious shock hazards that can result in se-
vere personal injury or death. Read and follow
these suggestions.

Keep the transfer switch cabinet closed and locked.
Make sure only authorized personnel have the cabi-
net and operational keys.

This symbol refers to a hazard or

This symbol refers to a hazard or un-

Due to the serious shock hazard from high voltages
within the cabinet, all service and adjustments to
the transfer switch must be performed only by an

electrician or authorized service representative.
If the cabinet must be opened for any reason:

1. Move the operation selector switch on the gen-
erator set to Stop.

2.Disconnect the starting batteries of the genera­tor set (remove the ground [–] lead first).

3.Remove AC power to the transfer switch. If the

instructions require otherwise, use extreme
caution due to the danger of shock hazard.

Place rubber insulative mats on dry wood platforms

over metal or concrete floors when working on any
electrical equipment. Do not wear damp clothing
(particularly wet shoes) or allow skin surfaces to be
damp when handling any electrical equipment.

Jewelry is a good conductor of electricity and
should be removed when working on the electrical
equipment.

Do not work on this equipment when mentally or
physically fatigued, or after consuming alcohol or

any drug that makes the operation of equipment un-
safe.

OT3-N-2

ii

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Redistribution or publication of this document
by any means, is strictly prohibited.

OPERATOR’S MANUAL

This operator’s manual provides information nec­essary for operation of an OT III transfer switch with
a nonautomatic/remote control.

TRANSFER SWITCH APPLICATION

Transfer switches are an essential part of a build-
ing’s standby (or emergency) power system. The

Normal power source, commonly the utility line, is
backed up by a Standby power source, often an

electric generating set. A transfer switch supplies
the electrical load with power from one of these two

power sources.

The load is connected to the common of the transfer

switch (Figure 1-1). Under normal conditions, the
load is supplied with power from the Normal source
(as illustrated). If the Normal power source must be
interrupted, the load is transferred to the Standby
power source. When Normal power returns, the
load should be retransferred to the Normal power

source. The transfer and retransfer of the load are
the two most basic functions of a transfer switch.

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FIGURE 1-1. LOAD TRANSFER SWITCH

(TYPICAL FUNCTION)

SC1101

Operation of a nonautomatic/remote transfer
switch is initiated either by an operator at the trans-
fer switch or by an external signal from a remote
source.

MODEL IDENTIFICATION

Identify your model by referring to the Model and
Specification number as shown on the nameplate.
Electrical characteristics are shown on the lower
portion of the nameplate, which is located on the
cabinet door.

If it is necessary to contact a dealer or distributor re-

garding the transfer switch, always give the com-
plete Model, Specification, and Serial number. This
information is necessary to properly identify your
unit among the many types manufactured.

1-1

HOW TO OBTAIN SERVICE

Redistribution or publication of this document
by any means, is strictly prohibited.

When the transfer switch requires servicing, con-
tact your nearest dealer or distributor. Factory-
trained Parts and Service representatives are
ready to handle all your service needs.

If unable to locate a dealer or distributor, consult the
Yellow Pages. Typically, our distributors are listed
under:

GENERATORS-ELECTRIC,
ENGINES-GASOLINE OR DIESEL, OR
RECREATIONAL VEHICLES-EQUIPMENT,
PARTS AND SERVICE.

For the name of your local Cummins  /Onan  or
Onan-only distributor in the United States or Can­ada, call 1-800-888-ONAN. (This automated serv-

ice utilizes touch-tone phones only.) By entering
your area code and the first three digits of your local
telephone number, you will receive the name and
telephone number of the distributor nearest you.

For the name of your local Cummins-only distribu­tor, or if you need more assistance, please call

Onan Corporation, 1-612-574-5000, 7:30 AM to
4:00 PM, Central Standard Time, Monday through

Friday.

When contacting your distributor, always supply the
complete Model Number and Serial Number as
shown on the nameplate.

Cummins is a registered trademark of Cummins Engine Company.
Onan is a registered trademark of Onan Corporation.

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