DOL(Direct on line) starters for Three phase motors

Direct on line starting is a starting technique of three phase induction motors.During starting period induction motors will draw more starting current,which is six times greater then normal rated current of that motor.so it is important to reduce the starting current,for these purpose starters are widely used.There are different types of starters they are

1. Direct online starters
2. Star delta Starters
3. Auto transformer starters

Wiring of DOL Starter

1. Main Contact

• Contactor is connecting among Supply Voltage, Relay Coil and Thermal Overload Relay.
• L1 of Contactor Connect (NO) to R Phase through MCCB
• L2 of Contactor Connect (NO) to Y Phase through MCCB
• L3 of Contactor Connect (NO) to B Phase through MCCB.

NO Contact (-||-):

• (13-14 or 53-54) is a normally Open NO contact (closes when the relay energizes)
• Contactor Point 53 is connecting to Start Button Point (94) and 54 Point of Contactor is connected to Common wire of Start/Stop Button.

NC Contact (-|/|-):

• (95-96) is a normally closed NC contact (opens when the thermal overloads trip if associated with the overload block)

2. Relay Coil Connection

• A1 of Relay Coil is connecting to any one Supply Phase and A2 is connecting to Thermal over Load Relay’s NC Connection (95).

3. Thermal Overload Relay Connection:

• T1,T2,T3 are connect to Thermal Overload Relay
• Overload Relay is Connecting between Main Contactor and Motor
• NC Connection (95-96) of Thermal Overload Relay is connecting to Stop Button and Common Connection of Start/Stop Button.

Working principle of DOL Starter

The main heart of DOL starter is Relay Coil. Normally it gets one phase constant from incoming supply Voltage (A1).when Coil gets second Phase relay coil energizes and Magnet of Contactor produce electromagnetic field and due to this Plunger of Contactor will move and Main Contactor of starter will closed and Auxiliary will change its position NO become NC and NC become (shown Red Line in Diagram)  .

Pushing Start Button

When We Push the start Button Relay Coil will get second phase from Supply Phase-Main contactor(5)-Auxiliary Contact(53)-Start button-Stop button-96-95-To Relay Coil (A2).Now Coil energizes and Magnetic field produce by Magnet and Plunger of Contactor move. Main Contactor closes and Motor gets supply at the same time Auxiliary contact become (53-54) from NO to NC .

Release Start Button

Relay coil gets supply even though we release Start button. When We release Start Push Button Relay Coil gets Supply phase from Main contactor (5)-Auxiliary contactor (53) – Auxiliary contactor (54)-Stop Button-96-95-Relay coil (shown Red / Blue Lines in Diagram).

In Overload Condition of Motor will be stopped by intermission of Control circuit at Point 96-95.

Pushing Stop Button

When we push Stop Button Control circuit of Starter will be break at stop button and Supply of Relay coil is broken, Plunger moves and close contact of Main Contactor becomes Open, Supply of Motor is disconnected.

Household ceiling Fan(Type:Single phase Induction Motor) Connection.

Generally Single phase induction motor of capacitor split type is widely used in household ceiling fans, many of us have doubt how to connect it to drive and feel comfortable beside it.Here is the solution grab it

These type of motors consists of two winding 

• Starting winding(Winding with less number of turns and thin in size)
• Running winding(Winding with high number of turns and thick in cross section size)

Components need are

1. Condenser of 2.5 micro farad 440/230 vAc.
2. 230V,50Hz AC mains

Circuits diagram above illustrates the connection of that wiring

•  From motor 4 or 3 wires will come out,Check that using Multimeter by seeing continuity test.
• If 3 is out ,one with thick wire is one end of running winding another with thin wire is one end of starting winding,internally both another ends are shorted and neutral is taken.
• Connect the condenser in series with Running winding,theoretically which is going to split the phase to produce rotating magnetic field. 
• Connect the Circuit to 230V AC mains Safely, And operate it.
• Good luck.

Testing 40Watts Tubelight choke

Previous blog explains, how to ignite tube light,but before giving connections,we need to check whether the choke is in good condition are not. This blog explains that

Above is the circuit diagram for that

Components required for checking are as follows

• 230v,50 Hz, Ac supply mains
• Testing 40W tubelight choke
• 100watts,230V Incandescent lamp

Connect the components as per in the circuit diagram, and Switch On the Supply mains Safely.

Conditions

1. If the bulb glows bright  ====>  Choke was Not good to connect
2. If the bulb glows dim     ====>  Choke is good to connect
3. If the bulb does not glows ===>  Choke was Not good to connect

Tube light wiring

1)In order to lighten a dim area, we to ignite a light,So It requires

• 40Watts 230v Argon gas fluorescent Tube light
• Tube light Frame
• 0.4Amps,40watts,230v  Choke
• 40Watts,230V Starter
• 230vAc Main Supply with Frequency 50 to 60 Hertz.

2)Wiring circuit diagram is shown above,If it is ok to use,use it.other wise follow the below steps.

• Connect the 230v phase wire to one end of choke
• connect another end to the tube light holder left below side.
• connect tube light holder left above side to one end of starter holder.
• Another end of starter holder is connected to right end up side of tube light holder.
• tube light holder right below side is connected to the neutral point.

3)Now connection is over,connect the bulb and checking all safety measures, give the supply.And this is only applicable for 230V 50Hz main supply.

4)Good luck