Briggs & Stratton 86262GS, Familiarization & Troubleshooting Manual

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Section 2 • Generator Components & Systems
Portable Generator Familiarization & Troubleshooting Guide
Protective Switches
Fuses
A fuse could be called a switch because it functions to open
an electrical circuit when current flow becomes excessive.
The fuse in Figure 2.21 is a strip of metal with a known
melting point that has been installed in series with the circuit
it is meant to protect.
Should current flowing through the fuse exceed a specific
value, the fuse element (strip of metal) melts which opens
the circuit. Generally, fuses are rated at the current value (in
amperes) at which its element will melt open.
Circuit Breakers
Circuit breakers (Figure 2.22) protect one or more circuits
against overloads or short circuits.
One type of circuit breaker consists of an electromagnet
with coil windings that are in series with the circuit to be
protected.When current flow exceeds a pre-determined
value, the coil’s magnetic field becomes strong enough to
open a set of contact points and open (or break) the circuit
before damage can be occur.
NOTE:
A “circuit breaker” may be reset manually
while a “fuse” must, generally, be replaced.
Thermal Switches
Thermal switches react to changes in temperature. One type
of thermal switch consists of a fine metal strip in which two
different metals having different expansion rates are welded
together.When the two different metals are heated, the
metal strips bend, which then opens (breaks) a set of
contacts.
Figure 2.23 illustrates two different types of thermal
switches.
The switch shown in “A” must be reset manually once it has
been tripped. In ”B,” the thermal switch resets automatically
after the metal has cooled to a pre-established temperature.
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Figure 2.21 — A Typical Fuse
Figure 2.23 — Examples of Thermal Switches
Figure 2.22 — Typical Circuit Breakers