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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 else can I help you with?
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.
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.
Are contactor points and bimetallic strip connected to the star delta starter of 3 phase induction motor?
yes
How do you select contactor for motor?
With a contactor we can control the power connection to the motor (power on/off). A typical AC contactor comes with 4 terminals aside (L1,L2,L3,A). 'A' has A1,A2 terminals which are of the magnetizing coil. By magnetizing & demagnetizing A1-A2 coil, power line connections to motor can either be made or broken. This is a simple DOL (Direct On Line) application. Further, reverse/forward circuits and star-delta circuits can be constructed based on the requirement. A contactor's role in whatever application is 'making or breaking' the contact. The coil supply can either be AC or DC.
How to choose rating of contactor in star delta starter?
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.
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.
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.
How do you change star to delta?
In motor starters, this is usually done using contactors. Explanation of this can easily be done using a circuit diagram. There are three contactors, the main, star and delta contactors-all these contactors can be the same type. There are many ways of wiring a star delta but here I will only give a generalized answer. First, the main contactor and star contactors are energised thus the motor runs in star. After about 5 seconds, the timer which gets energized at the same time as the main and star contactors, switches its CONTACTS i.e the normally open closes and the normally close opens. This dienergize the star contactor and energized the delta contactor. Thus, the motor now runs in delta.
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.
How can you include phase failure relay in your star delta motor starter circuit?
The star delta motor starter circuit has to have a control voltage to energize the motor magnetic contractors. A phase failure relay monitors all three phases of the incoming supply lines. The phase failure relay also has auxiliary contacts on it. There are usually two sets of "C" form contacts. The control voltage for the starter circuit must be connected across the normally open (N.O.) contacts of one of these two sets. When the phase monitor is energized these N.O. contacts close supplying the control voltage to the circuitry of the star delta starters. If there is a phase interruption, phase reversal or phase loss, the phase failure relay will de-energize and the N.O. contacts will go back to their de-energized state. If the star delta motor starter is in use at the time, its control circuitry voltage will be lost and the delta motor magnetic contactor will open. The opening of this contactor will disconnect the motor from the failed three phase supply.
What is the imporatance in using wyne delta motor control?
the important is contactor, timer, olr.....
What size contactor required for 110kw 415v star delta start motor?
240 or 415
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.
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.
Are contactor points and bimetallic strip connected to the star delta starter of 3 phase induction motor?
yes
How do you select contactor for motor?
With a contactor we can control the power connection to the motor (power on/off). A typical AC contactor comes with 4 terminals aside (L1,L2,L3,A). 'A' has A1,A2 terminals which are of the magnetizing coil. By magnetizing & demagnetizing A1-A2 coil, power line connections to motor can either be made or broken. This is a simple DOL (Direct On Line) application. Further, reverse/forward circuits and star-delta circuits can be constructed based on the requirement. A contactor's role in whatever application is 'making or breaking' the contact. The coil supply can either be AC or DC.
