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
Year: 2014
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
ACIM is the most popular motor for industrial and consumer applications. This is due to many factors such as the lack of commutator/brushes (high reliability), high efficiency at high loads and the ability to connect directly to the AC line. ACIMs have a classic three-phase stator and commonly have a
Similar to BLDC motors, PMSMs have a three-phase stator and a rotor with surface/interior-mounted permanent magnets. A PMSM provides rotation at a fixed speed in synchronization with the frequency of the power source. PMSMs are therefore ideal for high-accuracy fixed-speed drives. Boasting very highpower density, very high efficiency and high
BLDC motors have a three-phase stator winding and a rotor with surface-mounted permanent magnets. A BLDC motor does not have a commutator and is more reliable than a DC motor. The digital control and power electronics replace the function of the commutator and energize the proper winding. They are used
