Holiday Neptune 2004, Owner'S Manual

Page: 321 / 416

ELECTRICAL SYSTEMS - CHASSIS --- SECTION 9 • 321
NEPTUNE 2004
9
1. The 30 post is the incoming fuse and/or breaker power. Some relay
applications supply power to the 30 post, some use it for ground. The
30 post can be used many different ways.
2. The 85 post is one side of the coil, tripped different ways.
3. The 86 post is the opposite side of the coil, tripped different ways.
4. The 87 posts are not common to the 30 post until the relay is tripped.
When the relay trips, both 87 posts are common to the 30 post.
5. Using an 87a relay, the 30 post and the 87a post are common. When
the coil is tripped, the 87a post becomes inactive and then the 30 post
becomes common to the 87 post located on the outside of the relay.
A Single Pole Single Throw relay (SPST) is an electro-magnetic
switch consisting of a coil (terminals 85 & 86), 1 common terminal
(30), 1 normally closed terminal (87a), and one normally open
terminal (87).
When the coil of the relay is at rest (not energized), the
common terminal (30) and the normally closed terminal (87a)
have continuity. When the coil is energized, the common terminal
(30) and the normally open terminal (87) have continuity.
NOTE: When there is power applied to the coil, the coil sets up a
magnetic field in the windings. When the power is removed, the
field collapses. A momentary high voltage discharge will occur.
This is how an ignition coil works.
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