Single Phase Motor DOL Starter panel
Working Principle, control circuit & Connection diagram.
1- Single Phase DOL Starter:
Single-phase motor starter panel is used in commonly in everywhere. It is known as single-phase direct on-line starter. It is used in pumps, fan, cooling compressors, mixers, exhaust fan, blowers etc. the capacity rating of single-phase motor starter as.25,.5,.75, 1, 2 and 3 HP.
2- Control and connection diagram of single phase starter.
3- Working principal of single phase DOL starter.
DOL single phase working principle is two types as manual and auto mode. Both below mentioned details.
1- Manual Mode:
- First check the voltage in voltmeter. Press the start push button then contactor coil is energized. Double pole contactor is used for phase and neutral. Due to electromagnetic force the contactor pole is connected with supply input output terminal. After holding contactor, the induction motor start running.
- After starting motor, the start push button gets free from pushing. The contactor coil is energized continue after closing auxiliary normal open contact. Normal open contact is connected to the start button input terminal.
- For stopping induction motor then stop button is pressed. After pressing stop button contactor coil is de-energized and contactor latch is disconnected from terminal. Motor is stopped.
2- Auto Mode:
- First check the voltage in voltmeter.
- Select the selector switch as auto mode then contactor coil is energized. Double pole contactor is used for phase and neutral. Due to electromagnetic force the contactor pole is connected with supply input output terminal.After holding contactor, the induction motor start running.
- After starting motor, the holding supply of contactor coil is received from terminal of selector switch and coil will hold continue.
- If the power supply is switched off then the contactor coil will be de-energized. Contactor terminal points will be disconnected and motor will stop.
- If we want to stop the motor then we will have to select the selector switch on neutral mode or off mode then thecontactor coil is de-energized and contactor latch is disconnected from terminal. Motor is stopped.
4- Parts of Single Phase DOL:
1- Electrical panel body:
It is made with mild steal as box type with cover. In side box is used for main working parts like as miniature circuit breaker (MCB), Contactor, overload relay, control MCB, Connection plate etc.
Box cover is used for controlling parts like as start, stop push button, indicators, voltmeter and amp meter, auto manual selector switch. Starter panel size can be varied as per capacity.
2- MCB:
It is miniature circuit breaker.it is used for controlling incoming power supply. Different type MCB are used in electrical system but for direct on-line starter the TP MCB are used which is donate for three phases and neutral as R, N.
3- Single phase preventer.
It is known as protection device for detecting phase and neutral supply. if any phase or neutral is disconnected as accidentally then it detects and stop the motor. it can be reset as manual after checking power supply.
4- Contactor.
It is used as switch for incoming and outgoing power supply to the motor. it is controlled with low voltage coil whichis operated 24 and 230 voltages for making and breaking power supply to the motor.
5- Overload relay.
Overload relay is used for motor protection from overload and short circuit. It is installed after main contractor. It has many loads settings sot that according requirement load can be set as per motor actual load. After tripping motor, the overload relay can be reset.
6- Fuse or control MCB:
Controlling MCB is used for control circuit, R phase MCB is used for protection of voltage measuring circuit. As same type Y phase and B phase MCB are used for protection of voltage measuring circuit. As per capacity it can be used single pole 2amp or 5amp.
7- Indicators.:
Indicators are used for getting status of starter which is on, off or trip, power supply phase and neutral. It is available in market for different color codding.
Indicator indicates of panel status in different color codding as red, blue, yellow, ambler, green etc. It is available or used in 110 voltage or 230 voltage power supply
8- Amp and volt meter:
Measuring meters are used for measuring voltage and current. it is available in two types one is analogue type and other is digital type. Analogue meter is used separately but digital type meter only one.
9- Selector switch:
Selector switch is used for selecting auto and manual mode start of starter, voltage selector switch, amp selector switch. Voltage selector switch can be used for phase vise voltage selecting and amp selector switch is used of phase wise current measuring in amp meter.
10- Push button.
Push buttons are used for starting and stopping of starter. Start push bouton is green color and stop push button is red color.
11- Connection plate.
It is known as terminal plate or connector plate. It is made by Bakelite and available in according current ratings.
12- Capacitor:
Capacitor are connected in series with starting winding. It is main function for increasing magnetic torque on the rotor for starting because the rotor is required a lot of torque in starting for moving. It is works as split phase in single phase motor and increasing magnetic torque during starting.
