Solenoid relays are typically used to remotely switch a heavier current circuit than can be switched using common low amperage switches.
They solve the problem of being able to switch a high current circuit in a difficult-to-access location (say, an engine starting motor), without having to run heavy gauge wires all the way to a switch panel in a more convenient location.
By using a solenoid, less expensive smaller gauge wires can be run between the control switch in an electrical panel or dashboard and the solenoid, which is placed close to the actual high amperage load — an engine starter, windlass or winch motor, or a large pump, etc.
Common "Standard" solenoids are mid-to-high current rated relays (switches) that stay in the switched state as long as a switching signal is applied - often via a momentary switch, like the ignition switch in an automobile.
Solenoid relays are available in a variety of configurations, duty cycles, and performance ratings to match various applications.
The use of solenoids, where the actual high current switch contacts are contained in a closed housing, mnimizes arcing and contact oxidation, and makes for a longer service life.
Solenoids can come with insulated or grounded housings. Often, an insulated housing has two studs for the control circuit (one positive, one negative), while a grounded housing has a single control stud (positive) with the housing and its mounting bracket becoming part of the circuit (like the grounded starter solenoid in your car) — however there are exceptions to both of these examples.
Features of the #24115 solenoid -
• SPST (Single Pole Single Throw) with normally open contacts
• Single circuit: Off-On
• Voltage: 12 volts DC
• Maximum continuous current: 85 amps
• Plated steel housing; hex nuts and washers included
• NOTE - Grounded case
• Large (power circuit) battery studs; copper, 5/16"-24 thread
• Small (control circuit) coil studs; steel 10-32 thread
Click here for additional information and technical data about Standard Solenoids.
Note- Never unscrew the inner hex nuts on the studs. These keep the stud, as well as its internal wire connection in place.