Electrical polarity means that an electrical circuit has a positive and negative pole. A common question that is asked about solenoid valve coils is whether polarity needs to be considered. The simple answer is that polarity does not matter on solenoid valve coils.
These cables connect the battery to your car's starting system. First, the red one connects the starter solenoid to its positive terminal. This wire is usually live, so be careful when handling it. Then, a black or greenish-yellow cable connects the starter motor to the battery's negative terminal.
In most cases, it doesn't matter which wire goes where. However, there are a few circumstances when the order of the wires does matter. For example, if the solenoid is controlling a switch, it's important to make sure that the load wire is connected to the correct terminal. Otherwise, the circuit may not work properly.
Solenoids only operate in one direction.
Solenoids don't usually have a polarity so reversing the the current results merely in a reversal of the magnetic flux. However, Solenoids operating from DC should always have a Diode connected opposite to the polarity of the supply to prevent the high voltage spike that will be generated at switch-off.
Solenoids, like most valves, are directional. If you install it backward, it isn't going to work correctly. This is why. Solenoids must be sized properly.
Link the starter cable to the large bolt on the right of the Solenoid and the control wire to the control circuitry. Attach the other small cable to the ignition bypass terminal on the right of the Solenoid and reconnect the black negative wire.
If the direction of current is anti-clockwise, the end of the solenoid acts as a north pole and vice-versa.
If the current in the coil facing you is flowing in clockwise direction then its the south pole. If the current is flowing in anti-clockwise direction, then its the north pole. This can be figured out using Right hand thumb rule.
Note: The polarity of a solenoid can be reversed by reversing the direction of the current.
The small terminals are for the ignition coil and starter control wire that connects to the ignition or starter switch. One large terminal is for the battery cable from the positive battery terminal. And the other large terminal is for the wire that sends voltage to the starter motor itself.
A starting solenoid typically has four terminals: two for the high current circuit and the other two for the low current terminals, which are connected to the inner coil and activate the high current device on the high power end. The connectors are 2 tiny solenoid switch connections.
The positive (red) wire usually is connected by solenoid points activated by a lower amp wire to prevent higher amps passing through key connect or push button.
The field lines inside the solenoid are in the form of parallel straight lines. Which indicates that the magnetic field is the same at all points inside the solenoid. i.e. the field is uniform inside the solenoid. The magnetic field of a current carrying solenoid is used in making electromagnets.
The direction of the field due to coil or solenoid carrying current can be determined by using right hand rule. When you curl your right hand fingers in the direction of current,thumb gives the direction of magnetic field.
A current carrying solenoid behaves like a bar magnet with fixed polarities at its ends.
An electric current passes through a solenoid, resulting in a magnetic field. When you wrap your right hand around the solenoid with your fingers in the direction of the conventional current, your thumb points in the direction of the magnetic north pole.
The direction of the flow of the magnetic field in a solenoid is from the north pole to the south pole.
We can determine the north and the south poles of the solenoid by bringing a north pole of a magnet near to anyone end of the solenoid. If the magnet is attracted it is unlike pole (south) and if it is repelled it is like pole (north).
While the majority of solenoids are designed to pull, a simple design change can allow them to push. The only modification necessary is to extend the internal end of the plunger with a pushrod.
Magnetic Field Direction Around a Solenoid
Just like a bar magnet, the magnetic field exits through the North Pole of the solenoid and enters through the south. Inside the solenoid, the magnetic field moves from south to north.
A current carrying freely suspended solenoid behaves just like a bar magnet. Hence, it rests in the North-South direction exactly in the same manner as a bar magnet does.
As illustrated here, a typical starter solenoid has one small connector for the starter control wire and two large terminals. These two large terminals are for the positive battery cable and the thick wire that powers the starter motor.
With the solenoid with the 2 small terminals, one side is required to be the ground while the other is the power closing the circuit.