A Website on Maintenance of Electrical Systems

  A Magnetic Overload relay works by detecting the magnetic field strength generated by the current flowing to the motor.  In most cases the relay input is a representation of the  current (through C.Ts)  flowing into the motor.   The Magnetic Overload Relay is built in such a way that the magnetic flux set up by current flowing through the  coil  drags (pulls) the core upward. A typical dashpot type magnetic overload relay is shown in the image below.                                    Construction. The relay consists of two main parts which is the trip mechanism at the top and the dashpot at the bottom.  The parts of the relay are further divided into a coil, a plunger (core), an oil-filled dashpot and switching contacts (trip contacts). The plunger is attached to a piston (disc). The piston is suspended in an oil filled chamber....

  Leading power factor means that the current leads the voltage.  In other words, the load is capacitive.  If the real power load is 10kW at unity power factor, the kVA is 10kVA.  If the real load power is 10kW at  0.95 power factor (Leading Or Lagging),  kVA is 10.52kVA. The effect of leading power factor on the network are as follows 1) More current would flow in the circuit, this current could go above the cable ratings and higher current means bigger cables. S = VA Where: S =  10.52kVA =  10520VA V = 415 A  =? 10520 = 415 x A A = S/V = 25.35A in the circuit instead of 24.1A at unity PF 2)  Leading power factor will boost the output voltage of the supply generator. This happens due to over excitation of generators. (Leading PF causes high voltage in the circuit)  When Electrical devices equipment's are supplied with a voltage higher that its rated voltage, equipment damage/failu...

 What is a Neutral Link? Neutral links are metallic bars that are usually constructed of copper, aluminum or brass and act as an  electrical terminal in an electrical circuit . Below is an image of a neutral link.   The neutral link serves as termination point of the neutral of all individual circuits. The Neutral serves circuit return path or path completion line. Current that flows to the load returns trough the neutral, now since the neutral link is a neutral point for various circuits, it is designed to withstand a high amperage. Back to the question  why link is provided in neutral of an AC circuit and fuse in phase of AC circuit? Suppose there is no neutral link and a fuse is put on the live line and also in the neutral of a single-phase circuit.   In the event of a phase to neutral fault, very high current would flow in the circuit on both live line and neutral and the fuse would blow. Bot...

 DC Injection braking is a method used to rapidly decelerate and stop the rotor of AC induction motors without using friction.  Application And principle Of Operation. A typical application of this is in the tripper car conveyor system above, the tripper car is driven by direct-drive motors coupled to the tripper wheels. The car can move freely(forward and backward) on the rail and the car is stopped at precise locations to discharge product. The image below would give you a clearer understanding. We don't want a situation where we stop the electric motors but the car continues to roll. This is undesirable because you would struggle to stop the tripper car at the exact point where you want to discharge the products. It could also create a dangerous situation where you stop the car but, the moment of inertia could roll the car until it hits the mechanical stoppers at the end of the rail, potentially derailing the car. Electronic brakes are desired due to the fact that they have...