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The DC between windings is analogous to DC on capacitor plates. Windings, like capacitors, require time to charge up to the applied voltage, at which, there will be a constant current. Since Voltage / current= Resistance, the Megohm reading will change/increase until the windings are fully charged to a quiescent, steady leakage current. When current is at a stable leakage level, you will have an accurate reading.
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Why transformer ratio is secondary winding voltage by primary winding voltage but not primary winding voltage by secondary winding voltage?
The transformer primary winding is connected to the alternating current supply. This causes a varying current in the primary winding, which creates a varying magnetic field in the transformer core. Because the primary voltage is alternating, the flux is also alternating - expanding and contracting, and changing polarity in time with the supply. This alternating core flux 'cuts' the secondary winding/s of the transformer, and induces a voltage in the secondary coil/s. As long as there is a magnetic field that is moving, and a conductor for it to move across, it will induce a voltage in the conductor. While the actual induced voltage depends on the amount of flux, the amount of conductor material and the rate of change of the flux, the actual voltage can be calculated from: Vsec = ((Vprim * Nsec) / Nprim) where V = voltage, N = number of turns of wire in the coil, prim = primary and sec = secondary. Transformers don't work on DC - they give a brief pulse out at switch-on and switch-off, because that's the only times the current is changing and the flux is moving. If you have to transform DC, you use a switching circuit that 'chops' the DC into a series of pulses that simulate AC as far as the 'moving flux' requirements of the transformer are concerned.
Why am you losing half the voltage when rectifying secondary side of center-tapped transformer to DC via two 1n4007 diodes?
I think the answer is: if you input voltage to a grounded center-tapped secondary transformer winding, only 1/2 the voltage is applied to each rectifier at a time (sine wave), therefore the rectified voltage measured would be 1/2 that of the total voltage. The peak voltage would be 1.4 x RMS. Hope this helps.
Why is open ckt test conducted on lv side?
in the open circuit test, the high voltage winding is open circuited and the measurements are made on the low winding side i.e, the open circuit test is performed on the L.V side. This is because if the measurements are made on HV side then voltage applied must be large and the current would be unsuitably small, for which the high voltage sources may not be readily available and at the same time the instrument ranges required should be very high, Also the result obtained may not be accurate. NOTE: iron loss will be same, if measured from either of the winding. in short circuit test. the low voltage winding is short circuited and the measurements are made on the high voltage winding side i,e,. the sort circuit test is performed on H.V side. This is because if the test is performed on the L.V side, the current will be suitably large for which the instruments used should be of very high ranges. moreover instruments of such high ranges and the auto-transformer capable of handling such high currents may not be readily available.
What will happen if DC supply is given to the transfomer?
A capacitor resists a change in voltage. Initially, a capacitor given a DC voltage will appear to have very low resistance, but as current flows and time goes by, the resistance will increase as the voltage approaches the applied voltage. At equilibrium, the voltage across the capacitor will be equal to the applied voltage, the current will be zero, and the resistance will be infinity.
Which winding has the higher resistance start or run in single phase motors?
start winding is thicker with less number of winding whereas run winding is less thicker than start winding but with more number of winding. As we know inductance depends upon numbers of turns of winding so run winding will have more inductance.
What is an oiled transformer?
Di-Electric oil to cool the windings inside the transformer, There is a primary winding(high voltage) and a secondary winding(Lower Voltage), Usually stepping down the voltage to about 170 Volts for residential houses, It about 120 Volt by the time it gets to your panel.
What is an oil-insulated transformer?
Di-Electric oil to cool the windings inside the transformer, There is a primary winding(high voltage) and a secondary winding(Lower Voltage), Usually stepping down the voltage to about 170 Volts for residential houses, It about 120 Volt by the time it gets to your panel.
What will happen if you give DC input to the primary of a transformers?
If DC voltage is applied to the primary of a transformer the flux produced in the transformer core will not vary but remain constant in magnitude therefore no emf will be induced in the secondary winding except at the time of switching on.Also there will be no self induced emf in the primary winding to oppose the applied voltage and since the resistance of the primary winding is quite low heavy current will flow through it which may result in burning out of primary winding.
Why transformer ratio is secondary winding voltage by primary winding voltage but not primary winding voltage by secondary winding voltage?
The transformer primary winding is connected to the alternating current supply. This causes a varying current in the primary winding, which creates a varying magnetic field in the transformer core. Because the primary voltage is alternating, the flux is also alternating - expanding and contracting, and changing polarity in time with the supply. This alternating core flux 'cuts' the secondary winding/s of the transformer, and induces a voltage in the secondary coil/s. As long as there is a magnetic field that is moving, and a conductor for it to move across, it will induce a voltage in the conductor. While the actual induced voltage depends on the amount of flux, the amount of conductor material and the rate of change of the flux, the actual voltage can be calculated from: Vsec = ((Vprim * Nsec) / Nprim) where V = voltage, N = number of turns of wire in the coil, prim = primary and sec = secondary. Transformers don't work on DC - they give a brief pulse out at switch-on and switch-off, because that's the only times the current is changing and the flux is moving. If you have to transform DC, you use a switching circuit that 'chops' the DC into a series of pulses that simulate AC as far as the 'moving flux' requirements of the transformer are concerned.
How can you select motor for your required pumps?
WATER availability,line voltage,pump set head in meter,power rating,continuous time rating,prefered copper winding
What is transformer polarity?
'Polarity' describes the sense (direction) in which the voltage (not current!) induced into secondary winding is acting, relative to the sense in which the voltage applied to the primary winding is acting.In North America, a transformer's high-voltage winding terminals are identified by the letter H, and the low-voltage winding terminals by the letter X. In the case of a two-winding transformer, the pair of high-voltage terminals are marked H1 - H2, and the pair of low-voltage terminals are marked X1 - X2.When the potential of HV terminal H1 'goes positive' (i.e. during the first half-cycle of AC), if LV terminal X1 also goes positive at the same time, then the transformer is an 'additive polarity' transformer. On the other hand, if terminal X2 goes positive at the same time as H1, then the transformer is a 'subtractive polarity' transformer.Knowing the polarity of a transformer is very important if you intend to operate transformers in parallel with each other (there are other factors, too, of course), in the same way as it is important to know the polarity of a battery before you can connect it in parallel with another battery.
Why am you losing half the voltage when rectifying secondary side of center-tapped transformer to DC via two 1n4007 diodes?
I think the answer is: if you input voltage to a grounded center-tapped secondary transformer winding, only 1/2 the voltage is applied to each rectifier at a time (sine wave), therefore the rectified voltage measured would be 1/2 that of the total voltage. The peak voltage would be 1.4 x RMS. Hope this helps.
What happen if primary of transformer connected to dc?
Nothing noticeable. DC power is not transmitted between the coils of a transformer. There would be no current on the other side of the transformer, unless the power of the source was constantly modulated. bescause flux does not change its state.after some time excessive heat is produced and winding may burnAnswerA transformer's primary winding presents two forms of opposition to current flow. The first is resistance, which is dependent upon the length, cross-sectional area, and resistivity of the wound conductor. The second is reactance, which depends upon the inductance of the winding and the frequency of the supply. Resistance opposes both AC and DC currents, while reactance opposes only AC current. In the case of a transformer's windings, the resistance is relatively low while the reactance is very high. When an AC voltage is applied, the reactance is sufficiently high to limit the value of AC current flowing through the winding. However, the resistance is so low that a large current would flow if an equivalent DC voltage was applied instead. This current would likely overheat the winding's insulation, resulting in its breakdown, causing a short circuit(s) which could severely damage the transformer.
Why is open ckt test conducted on lv side?
in the open circuit test, the high voltage winding is open circuited and the measurements are made on the low winding side i.e, the open circuit test is performed on the L.V side. This is because if the measurements are made on HV side then voltage applied must be large and the current would be unsuitably small, for which the high voltage sources may not be readily available and at the same time the instrument ranges required should be very high, Also the result obtained may not be accurate. NOTE: iron loss will be same, if measured from either of the winding. in short circuit test. the low voltage winding is short circuited and the measurements are made on the high voltage winding side i,e,. the sort circuit test is performed on H.V side. This is because if the test is performed on the L.V side, the current will be suitably large for which the instruments used should be of very high ranges. moreover instruments of such high ranges and the auto-transformer capable of handling such high currents may not be readily available.
Polarity of six terminal induction motor winding is decided at the time of connection of winding?
Is there a question here.
What will happen if DC supply is given to the transfomer?
A capacitor resists a change in voltage. Initially, a capacitor given a DC voltage will appear to have very low resistance, but as current flows and time goes by, the resistance will increase as the voltage approaches the applied voltage. At equilibrium, the voltage across the capacitor will be equal to the applied voltage, the current will be zero, and the resistance will be infinity.
How does the 12 volts of battery steps up to 25000 volts?
Here is how the ignition system in a car works. In older cars, the battery supplies electricity to the ignition coil and ignition points. The ignition coil is actually a device known as a transformer. Transformers have at least 2 windings, and electricity from one winding is "induced" into the other winding when the field in the first winding collapes. In transformers, the thicker and shorter the wire, the more current is involved, and the thinner and longer a wire is, the more voltage is involved. Anyway, the primary coil is magnetized by the battery. When the ignition points open, that field collapses and the fading magnetism creates electricity in the secondary winding. The primary winding is made for current, while the secondary winding is made for voltage. Since there are many more windings (maybe over 2000 times the number used in the primary winding), the voltage is much higher. From there, the distributor cap determines which spark plug gets the high voltage. Everything is timed to where each spark plug gets a jolt of high voltage each time a piston reaches the top (and yes, this even happens on the exhaust stroke, though it does no good, at least in a traditional, non-computer engine). In modern engines, the principles are the same, though the methods are different. Instead of points, there is an ignition timing sensor, and it tells the ignition module when to fire or even where each piston is. That causes transistors or other semiconductors to build and collapse the magnetic field on the primary coil winding.
