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Autotransformers are absolutely safe when supplying a lower voltage load from a higher voltage source, and are used to do so. However, they do not provide isolation. If isolation is considered essential, then autotransformers are not appropriate.

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Q: Why autotransformers are not safe for supplying low voltage from a high voltage source?
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Why induction type instrument canot be used for dc measurements?

Induction is a property of voltage changes, which does not occur with Direct Current devices. There are exceptions, such as the coil of an automobile, which charges up to a high voltage between ignition discharges, but the voltage supplying the coil does not vary.


What are voltage dividers?

Voltage dividers are used in a linear circuit to separate the input voltage into a small portion known as the output voltage. It is commonly used to get a low voltage signal equal to the voltage being measured.


Why High voltage test for cables?

High voltage testing is performed to confirm the integrity of a cable's insulation. It is always carried out after a new cable has been installed and terminated, or whenever a new joint is installed.


How do design a high voltage voltmeter?

Use a voltage divider and an standard high input impedance voltmeter connected to the low voltage output tap of the divider. Just check that: a) the voltage divider has enough resistance to minimize loading of the voltage source (The voltage divider resistance should be as high as possible). b) the voltmeter's input impedance is at least 10-20 times larger than the output resistance (impedance) of the divider. If necessary add a high-input impedance amplifier or a transducer between the divider output and the voltmeter. What is high voltage for you?


Which one of the following statements is true of a split phase motor when it is starting the speed is high the torque is high the current is low the voltage is low?

The first statement is true, the motor needs a power source to operate.

Related questions

Why do protons move away from high voltage?

Protons respond to any voltage, and moreso to high voltage. If a proton is moving away from high voltage, it must be because the high voltage source is positive. A positive will repel a positive. Certainly if the high voltage was negative, the proton would be moving toward the source. The basic laws of electrostatics apply.


What would cause a motorcycle battery to explode while riding it?

Overcharging; most likely the altenator is at fault and supplying too high a voltage.


How is voltage measured?

Use a voltmeter with a high input impedance and measure at the source the voltage.


Why were instrument of a transformer placed on a high voltage side in short circuit test?

I assume "tension" in this question should be replaced with "voltage". Short circuit tests are often performed from the lower voltage side of the transformer, since a lower voltage source is then required to perform the test. Often times the test lab may not have a source that can output a high enough voltage to perform from the high voltage winding.


Where source and what parts of high voltage in ignition system of car?

The coil generates the high voltage charge which is then distributed to the spark plugs by the rotor arm in the distributor cap.


Why induction type instrument canot be used for dc measurements?

Induction is a property of voltage changes, which does not occur with Direct Current devices. There are exceptions, such as the coil of an automobile, which charges up to a high voltage between ignition discharges, but the voltage supplying the coil does not vary.


What are voltage dividers?

Voltage dividers are used in a linear circuit to separate the input voltage into a small portion known as the output voltage. It is commonly used to get a low voltage signal equal to the voltage being measured.


Why High voltage test for cables?

High voltage testing is performed to confirm the integrity of a cable's insulation. It is always carried out after a new cable has been installed and terminated, or whenever a new joint is installed.


What is the purpose of voltage transformer?

A 'voltage transformer' (called a 'potential transformer' in North America) is classified as an 'instrument transformer', and is used to reduce the voltage of an electrical system to a lower, safe, level for the purposes of either operating a voltmeter or supplying a protection relay. At the same time, it electrically-isolates the meter or relay from the high-voltage system.


What is the light source for the SEM system?

A Scanning Electron Microscope, or SEM, is a type of electron microscope. Its light source is from a beam of high voltage electrons.


Why the coil of a transformer donot get short circuited even though it is continuous wire?

If energized from the high side, the induced voltage in the secondary counter acts the current flowing in the primary (or pushes against the flow of current in the primary). This is a fundamental property governing the operation of induction - the induced voltage on a wire from another source will induce a voltage back on the source in the opposite direction of the source's voltage.


Why high voltage does not kill?

Its not voltage that kills it is current.High voltage CAN kill, if it can also provide high current (especially if the current comes near the heart as it takes under 1mA to stop the heart which isn't much current).However if the high voltage source is current limited and/or the current only passes through the extremities it is very unlikely to kill.