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Why used star contactor half value then main and delta contactor in star delta starter?
Wiki User
∙ 9y ago
This type of motor starting configuration is used to start large motors. The utility company's policy is to only let a certain three phase motor horsepower loads across the line starting. High horsepower loads draw high current which draws the line voltage down. This causes a small instantaneous brown out to which the utility company gets complaints about. To solve this problem, limit the horsepower load. Starting a delta motor in star configuration reduces the inrush current because the voltage applied to the motor is lower.
This technology is rapidly becoming old due to the new type of motor controllers on the market. Replacing the star delta starters is soft start controllers. The inrush current can be controlled so as to not make any voltage drop on the line. These controllers are different from VFD's which are expensive for this type of application. The main function of the soft start is to get the motor on line without any line disturbances.
Wiki User
∙ 9y ago
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The highest value reached by an alternating voltage in a half cycle is called?
maximum or peak value
What is average value in alternate voltage?
The term is 'alternating voltage', not 'alternate voltage'. For an a.c. voltage or current, the average value is taken over half its wavelength because, over a complete wavelength it is, of course, zero. For a sine wave, the average value (over half a wavelength) is 0.637 Vmax or 0.637 Imax.
Comparision between half wave and full wave rectifier?
A half wave rectifier conducts on every other cycle. The output is a train of half sine cycles, at a period equal to the input period. At 60 Hz, the period is 16.7 ms. Each half cycle (8.3 ms) will be interleaved with periods (8.3 ms) of no voltage. If you filter the output with a capacitor, you get DC - at no load, the DC will be the peak value less the forward bias voltage of the diode - at some load, the DC will fluctuate between that peak value and some value dependent on the size of the capacitor and the current draw. Again, the period (of this nearly sawtooth waveform) will be the input period. A full wave rectifier conducts on every cycle. The output is a train of half sine cycles, at a period equal to half the input period. At 60 Hz, the period is 8.3 ms. Each cycle (8.3 ms) will be connected to the preceding cycle with no intervening delay. Each cycle will pulse in the same direction, instead of in alternating directions. If you filter the output with a capacitor, you get DC - at no load, the DC will be the peak value less the forward bias voltage of the diode - at some load, the DC will fluctuate between that peak value and some value dependent on the size of the capacitor and the current draw. Again, the period (of the nearly sawtooth waveform) will be half the input period. Since the full wave output waveform is twice the frequency (half the period) of the half wave output, the capacitor can be about half its required value for the half wave circuit in order to achieve the same level of filtering.
What will the multimeter show if it is used to measure the voltage of the ac half wave rectified voltage?
rms value of voltage
Write a VB program for binary search?
The optimal binary search algorithm uses a sorted array as the data container. Define the range to be searched using a half-closed range of indices [begin:end). Initially, this will be the half-closed range of the whole array. The algorithm is as follows: If begin>=end, this would indicate the range is empty or invalid, thus the value cannot exist. We return the end iterator to indicate value not found. If the range has one or more elements, then we calculate the middle index of the range: middle = begin + (end - begin) / 2 Note: division takes precedence over addition. We then compare the value in the middle of the range with the value being searched. If they are equal, we are done, we simply return the middle index. Otherwise, if the value being searched is less than the middle value, we adjust the upper bound of the array so the next iteration only searches the lower half of the original range: new_end = middle Otherwise we adjust the lower bound of the array so the next iteration only searches the upper half of the range: new_begin = middle + 1 We then repeat the algorithm using the adjusted half-closed range. The algorithm can be implemented in Visual Basic as follows. Note the array, a, is passed by reference (ByRef) to prevent making an unnecessary copy of the array. The function does not make any changes to the array itself so there's no need to copy it. Function bin_search (ByRef a As Integer(), ByVal begin As Integer, ByVal end As Integer, ByVal value As Integer) As Integer ' save the end iterator (it may change later) Dim not_found As Integer = end ' while the range is valid... While begin < end ' calculate middle index Dim middle As Integer = begin + (end - begin) / 2 ' compare the middle element for equality If value = A[middle] Then ' value found! Return middle End If ' value not found, so determine which half of array to eliminate If value < A[middle] Then ' eliminate upper half (if value exists, it must be in the lower half) end = middle Else ' eliminate lower half (if value exists, it must be in upper half) begin = middle + 1 End If ' repeat algorithm... End While ' if we get this far, the range is either empty or invalid (begin>=end), so the value does not exist Return not_found End Function
Why is a star-delta starter used?
A "star-delta" starter- also known as a "Y-delta" or "wye-delta" starter - is used to reduce the voltage on the motor windings to only 1/.'/'3 [one divided by root 3] times the incoming line voltage, to help reduce mechanical stress and in-rush current at start-up.More detailWhenever you start a big heavy electric motor, you need to start it slowly to prevent the rotor overheating and drawing an enormous current. When the windings of a 3-phase motor are connected in STAR the voltage is reduced to a fraction equal to one over root three (1 / 1.732) times the normal running voltage that is used when it is connected in DELTA, resulting in a reduction of nearly one half the normal current.Once the motor picks up speed, the connection is changed to DELTA so that the motor runs at full speed and torque from then on. It's a bit like using the gears of an automobile.For more information please see the answers to the Related Questions shown below.
How do the Niger river's two delta regions differ?
In the Sahel it divides into a network of channels, swamps, and lakes. This network is known as the inland delta. The Niger's true delta on the Gulf of Guinea is very wide. Half of Nigeria's coastline consists of the delta.
What is a delta fold in the printing industry?
A FOLD AGAINST THE DIRECTION OF THE WEB 11 X17 IN HALF TO 11 X 8.5, THEN TO #10 ON THE DELTA FOLDER
Why is the half dime called a half dime?
Because the value of it is worth half the value of a dime.
Where is the starter on a 1997 Acura TL 3.2?
THE STARTER SITS RIGHT ABOVE THE POINT WHERE THE DRIVER SIDE HALF SHAFT CV AXLE ENTERS THE TRANSMISSION. YOU WILL HAVE TO REMOVE THE HALF SHAFT TO GET IT OUT.
What is a half-value layer?
Some previously called a half-value thickness or half-value layer a half-thickness. Whatever an investigator calls it, the half-value layer is the thickness a layer of a given material would have to be to reduce the intensity of radiation striking its surface by half (50%).
What is the value of 20 half dollars?
20 half dollars have a face value of a $10.
How do you change the starter on a 1993 mustang with 4 cylinder engine?
start by disconnecting battery, then wires on starter, then bolts on starter, if it drops on the pavement you are half done.... reverse procedure to install
What is value of 5 in diameter of half dollar?
value of 5 in the diameterof a half dollar
What is the value of a half cent?
A half cent is one half of one cent or 200 half cents = $1.00. If your asking about the value of a specific coin, a date is needed.
What is the value of an Arkansas half dollar?
It's a quarter, not a half, and it's only worth face value.
What is the value of a 1883 hawaiian half dollar?
The average value of circulated half dollars is $300.00- $500.00
