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As well as motors, contactors also have kW and Ampere ratings. Have a look on the name plate of your motor and you will see its maximum current draw (amps). Select a contactor with a current rating greater than this.
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Are contactor points and bimetallic strip connected to the star delta starter of 3 phase induction motor?
yes
What is wye-delta motor control?
It is a type of starter that allows a motor to be started across the line by starting the motor with a reduced inrush current. The motor is started in a wye configuration until it gets up to speed and then a timer drops the wye contactor out a draws the delta configured contactor in. The motor then operates in a delta wired configuration.
What usually cause the star contactor to burn on a star delta starter?
A lot of designers will fit an under rated star contactor, partly for cost saving purposes and partly down to the fact that the star contactor will only stay energised for a brief period. Burning out the star contactor could be down to it staying in circuit too long, not changing over to delta, a timer malfunction holding in the star contactor or switch that is defective in the control circuit. Another cause could be your motor is drawing excess current.
Does a star delta timer rely on the breaking of the retaining contacts on the star contactor side?
The N.C. (timed open) contacts in the star delta timer energize the star contactor's coil when the system is energized. At the same instant the system is energized, the timer starts to time down the required time which lets the motor get up to speed in the star configuration. When the timer reaches the set point time, a second set of N.O. (timed closed) contacts close the delta contactor's coil and open the N.C. timed contacts of star contactor's coil. The motor now runs in the delta configuration. When the system is de energized the timer contact's reset to its de energized state.
What is a manual star-delta starter?
In manual star delta starter, the change over from star to delta does not happen automatically. The operator or user puts on the starter, and after few seconds he pushes a lever or handle to change over to Delta. In automatic method, change over happens from star to delta using an automatic preset timer.
Are contactor points and bimetallic strip connected to the star delta starter of 3 phase induction motor?
yes
What is wye-delta motor control?
It is a type of starter that allows a motor to be started across the line by starting the motor with a reduced inrush current. The motor is started in a wye configuration until it gets up to speed and then a timer drops the wye contactor out a draws the delta configured contactor in. The motor then operates in a delta wired configuration.
What components can be changed on a contactor and a starter for rebuilding purposes?
Various components can be added and removed from a contactor. Auxiliary contacts can be inserted in front of the main contacts, as well as a time relay in the case of motor starters (star/delta starter). Usually you should fit a overload relay when you use the contactor in a motor starter, this is inserted in the main contacts at the bottom. However, the internal components like the coil may never be changed or replaced.
What usually cause the star contactor to burn on a star delta starter?
A lot of designers will fit an under rated star contactor, partly for cost saving purposes and partly down to the fact that the star contactor will only stay energised for a brief period. Burning out the star contactor could be down to it staying in circuit too long, not changing over to delta, a timer malfunction holding in the star contactor or switch that is defective in the control circuit. Another cause could be your motor is drawing excess current.
How much voltage does star-Delta starter give to motor at start?
A delta starter supplies what ever the supplied voltage to the line side of the contactor is. The inrush current is usually 300% of the full load amperage of the motor. Edit to above answer: Actually the question is for a Wye-Delta Starter (Wye=Star). There are two contactors, one in Wye configuration and one with Delta. The Wye is used to start and the Delta for run. This is a reduced voltage start scheme. Though the line supply voltage remains the same, for instance 480VAC, the phase voltage at the motor will be different for the Wye: V(phase) = V(line)/1.732 In a Delta V(phase) = V(line) So the Phase Voltage during the start will be 277VAC and then when the motor is spinning, usually after a set time delay, the Wye contactor drops out and the Delta contactor kicks in so that Phase Voltage is now the full 480VAC.
Why use link in star contactor?
The link in the star contactor is used to form the star point of three of the motor leads. On most star wound motors the star point is inside the motor windings. On a motor that can be used for star delta starting it is a six wire motor. The star point winding depends on the contactor to tie the coil ends together externally in the control panel of the star delta starter.
What size of electric motor that requires wye delta starter?
10 hp and above motor power rating....
Star delta motor what are the links across the terminal for?
That is the star point contactor that opens when it goes into the delta configuration.
Why star delta timer required for motor?
The timer is used to give the motor time to reach its running speed at the star voltage. Once the timer times out the star contactor drops out and the delta contactor pulls in.
In a star-delta starter what could be the problem if the motor does not rotate in star but rotates in delta?
One of the three phase contacts in the star contactor could be burned open or just open not allowing the motor to start because of a single phase condition. The time interval between star and delta connections could be small enough that the motor heaters will not catch the single phase condition and trip. When the motor goes into delta (which is now across the line starting) all of the three phase contacts in the contactor close and the motor starts.
What is the imporatance in using wyne delta motor control?
the important is contactor, timer, olr.....
What is a timer in a star delta starter?
A timer in star delta starter for a three phase motor is an electronic device designed to do the change over or transition from star connection - using which the motor suns on a reduced voltage and current and produces less torque - to the delta connection necessary for running the motor at its full power, using high voltage and current to produce a high torque. The timing interval that is set is dependent how long the motor needs to start up from standstill to normal speed. Some motors require 15 seconds for the initial startup in star connection and after that given value of time the timer signals to the star contactor to go to the open position and the main delta contactor to go to the closed position, thus forming the delta circuit.
