211 SRI RAMAKRISHNA MISSION VIDYALYA POLYTECHNIC COLLEGE.

 A rotor resistance starter uses a ladder diagram to control the gradual removal of external resistance from a slip-ring motor 's rotor circuit , starting with high resistance for low starting current and high starting torque , and ending with the rotor short-circuited for normal running. The ladder diagram consists of rungs that energize contactors sequentially via timers to gradually cut out resistors.  Ladder diagram ladder rungs A basic ladder diagram for a rotor resistance starter would include the following components:  Power supply: Three-phase AC power is connected to the starter. Motor Contactor (MC): The main contactor that connects the stator to the power supply. This is the first contactor to close. Timers : These are used to control the time delay for each stage of resistance removal. Resistor bank : Multiple steps of resistors are connected in series with the rotor circuit at the start. Shunt Contactors (S1, S2, etc.): Each shunt contactor is connected i...

  Synchronous Condenser An over-excited synchronous motor running on no-load is called the  synchronous condenser .  It is also known as  synchronous capacitor  or  synchronous compensator or synchronous phase modifier . A synchronous motor can deliver or absorb reactive power by changing the DC excitation of its field winding. It can be made to draw a leading current from the supply with over-excitation of its field winding and therefore, it supplies lagging reactive power (or absorbs leading reactive power).