Actuators are operated in the same way as solenoids. They are used to move mechanisms remotely. Some examples of actuators on a vehicle are, door locks, pre-engaged starter motors and fuel cut off valves. Consider the diagram below. Like a solenoid or relay an actuator has a winding. When current
A solenoid is the term used for a heavy duty relay and like a relay acts as a switch saver. Solenoids are used to switch circuits that require a very large current to operate. An example of this type of circuit is the starter circuit. Consider the diagram below. Since the
This is sometimes known as an ‘either/or’ relay because you can use either one circuit or the other. This type of relay is particularly useful for headlights. Pin number 87A feeds the dipped beam circuit. When the driver selects main beam the relay is energised so the moving contact moves to
Relays are used extensively in modern vehicles. They can be thought as electro/mechanical switches. They are often used to switch on circuits that require a heavy current e.g. the heated rear windscreen (H.R.W.) circuit. If a relay was not used the contacts inside the HRW switch would need to be
When the armature rotates a half a revolution ‘A’ is positioned at the south pole “S” and ‘B’ positioned at the north pole “N”. As the magnetic field surrounding ‘A’ is in the anti-clockwise direction the magnetic field would be stronger under ‘A’ and above ‘B’, which would mean that
To understand this rule, open your hand, as shown below, with the thumb pointing perpendicular to the index finger, and the index finger perpendicular to the middle finger. Then, point the index finger in the direction of the magnetic flux, and the middle finger in the direction of the current.
An electromagnetic force is a force that acts on a conductor when current flows in the conductor within a magnetic field. It is utilised to operate starter and wiper motors, and the pointers of ammeters, voltmeters, etc. DIRECTION OF ELECTROMAGNETIC FORCE Let’s assume the N and S poles of a
TESTS WHEN ISOLATED 1) VISUAL TESTS: Check that motor frame is mechanically sound. Remove terminal cover plate and check for ingress of foreign material, moisture etc. Check for signs of overheating, arcing or burning. Check ventilation is clear. 2) ELECTRICAL TESTS: Identify windings using a continuity tester. Measure the resistance
Electric motors and generators are referred to as electric machines. Electricians are most frequently concerned with electric motors, due to their extensive application. The electric motor must be one of man’s most useful inventions. In the manufacturing industries they are used in large numbers, to drive lathes, drilling and milling
SR motors do not contain magnets and are constructed such that both the stator and rotor have salient poles. The motor is driven by a sequence of current pulses applied at each phase, which requires control electronics for operation. The SR motor works on the principle that the magnetic circuit
