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D–2 976-0043-01-02
Two-Wire Start Circuits
Two-wire starting generators are the easiest to control and are highly
recommended for this type of application. A contact closure starts the
generator and opening the contacts stops the generator. These types of
generators also provide their own cranking control circuit, possibly oil
pressure and overtemp protection circuits, and are designed for
unattended operation applications.
Three-Wire Start Circuits
The common term “three-wire start” may be misleading, as the actual
number of wires required may be four or more. Control of the starter
motor is separate in these systems and the protection circuits found in
two-wire start systems may not be present. This could lead to the
generator running when it is in an over-temperature or low oil condition,
etc. Since these generators are not designed for unattended operation, the
generator supplier should be consulted regarding additional safety/
protection components that may be required.
Two well-known manufacturers of three-wire starting generators are
Honda and Onan. Each uses a different starting sequence and must be
wired accordingly.
Honda™ 3-Wire Type Generators
Honda 3-wire type generators incorporate a starting sequence similar to
an automotive starting system, the switch is first placed in the RUN
position then momentarily held in the START position. When the
generator has started, the switch is returned to the RUN position. To
STOP the generator, the switch is placed in the OFF position.
In this starting configuration, relay RY7 (in the RN1 mode) duplicates the
“RUN” position and RY8 duplicates the “START” position cranking the
starter motor.