MSD 8961 High Current Relay, SPST Installation - Manual

MSD RELAYS
PN 8961, Single-Pole, Double-Throw, 30 Amp/12 VDC
PN 8960, Double-Pole, Double-Throw, 30 Amp/12 VDC
MSD Relays will allow you to activate a variety of accessories that require high current. These are
ideal to tie in with an rpm activated switch to control a nitrous or air shifter solenoid.
The benefit of a relay is that it can be energized using a small amount of power (12V/1 Amp). This
moves the relay's armature so it can transfer a large amount of power (12V/30 Amp) to activate a
high current device.
• The PN 8960 will handle a 30 Amp load, on each side, with an input voltage of 12 volts.
• The PN 8961 Relay will handle a 30 Amp load and is ideal for multiple accessories.
Following is a short description of the operation of a relay. A variety of wiring schematics are also
included to help with your installation.
Relays are very simple devices and consist of four basic parts:
• A small coil (sometimes referred to as a bobbin or electromagnet)
• An armature
• A spring
• A set of electrical contacts
Relays consist of two separate and completely independent circuits; the Controller circuit and Switch
circuit. In Figure 1 the Controller circuit is on the bottom and it controls the power to the electromagnet.
When 12 volts are supplied through the switch, the coil is energized. When energized, it attracts the
armature of the Switch circut.
The Switch circuit consists of an armature, spring and contacts for the high current side. The armature
is a switch and will complete or open the high current circuit. When the coil of the relay is energized, it
attracts the armature from one electrical contact to another to complete the circuit. When the coil is not
energized the spring pulls (or pushes) the armature back and the high current circuit is opened.
Figure 1 General Relay.
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