Top Answer
User Avatar
Wiki User
Answered 2007-09-01 13:07:40

This depends on whether the voltage is AC or DC but an oscilloscope is the tool of choice for seeing voltages and how they change with time.

User Avatar

Your Answer


Still Have Questions?

Related Questions

How do you change the RPM of a motor?

For AC motor, you can change motor RPM by changing its supply voltage or by changing supply frequency. For DC motor, you can change motor speed by controlling armatyre voltage or field current.

What parts are needed to create a circuit?

A basic electrical circuit needs a voltage supply (battery or household outlet), wiring to carry electrons to and from the voltage supply to the load, and a load (motor, light, heat element, stereo, blender, whatever).

How do i switch a 3 phase motor from low to high voltage?

You can't. You must supply the motor with it's required voltage. If it's a dual voltage motor, follow the wiring schematic on the motor nameplate to switch from low to high voltage.

What are the differences between the parts of a generator and the parts of a motor?

In principle a generator is the same as a motor. In a dc motor the voltage generated by the rotating armature is slightly less than the supply voltage which causes power to flow in from the supply. If an engine is then coupled to the shaft causing it to rotate faster, then it generates more voltage and power flows back into the supply. That is how a motor becomes a generator.

How could you find the purpose of a parallel circuit?

For an electrical load, such as a lamp, heater or motor, to operate at its rated power, it must be subject to its rated voltage which always corresponds to the supply voltage. For this to happen, individual loads must be connected in parallel with the supply and with each other. So all the electrical loads in your home, in your car, etc., are ALL connected in parallel.

Vlotage on motor name plate is line or phase voltage?

The voltage tag on a motor says 120 or 220 volt and some motors have jumpers to wire it for either one. That is the supply line voltage. The motor knows how to use that. If the plate says three phase is required then consult your electic supply Company for a three phase supply line.

Could over-current be caused by low voltage?

No, not directly. The supply voltage has to rise or the resistance has to fall to get over-current. If there was a secondary control voltage that was part of a voltage control circuit for a higher voltage, it is conceivable that a voltage drop in control circuit could cause an over-voltage in the supply. Motors are constant power devices, so this could be true for a motor. If you have a 1hp motor (loaded at 1hp), it will want to draw 1hp of power no matter the supply voltage. If the voltage dips, the motor will require more current to keep it spinning at it's normal speed.

Can you connect three phase AC voltage directly to motor?

Physically yes, but its not to code. The motor that is connected to a three phase system has to have undervoltage protection and thermal protection to be complient to the electrical code. This is done with a three phase motor contactor. By using a contactor you have the ability to start and stop the motor. The overload protection is also combined with the contactor so if the motor gets into an overload state the contactor will automatically disconnct it from the supply. Also if there is a power failure when the motor was running the motor will be unable to start up again on resumption of power. The start button has to be pushed to re start the motor, (this is the under voltage protection). This is why the supply voltage is NEVER directly connected to a motor.

What is the voltage that supplies a motor starter called?

In the electrical trade it is called control voltage. This voltage can be any voltage. In North America the common control voltage is 120 volts.

Why starting current of the motor is high when it is directly connected to supply voltage?

When a motor is stationary, it is not generating a back-mmf which would otherwise act to oppose the applied voltage and, thus, reduce the supply current. However, as the motor runs up to speed, it generates an increasing back-emf, and the supply current falls.

What is the phase voltage inside a motor if one phase is lost and what is the voltage between the other two phases?

The phase voltage is usually constant and determined by the supply voltage.

Why does the induced emf known as back emf?

In a dc motor the voltage generated in the armature acts against the supply voltage. The current is the voltage difference divided by the armature resistance. If the rotor is turned faster so that the back emf exceeds the supply voltage, the current goes the other way and the motor has become a generator.

How much transient current for 930 kw motor?

The current depends on the supply voltage.

How do you wire a synchorous motor?

The simplest synchronous motor has two leads which must be connected to the live and neutral of the correct supply voltage as marked on the motor.

What happens when a motor is short circuited?

Shorting the motor's electrical supply will blow the fuse and the motor will run down and stop.

How do you run a motor 208 volts ac in a 230 volts suply?

If your motor is rated for only 208 volts you may not be able to use 230 volts for it. It will run, but may shorten the life of the motor. Motors are rated with a 10% tolerance for voltage. This means that a 208 volt motor has a maximum voltage rating of 228.8 volts. So measure you voltage supply and see if it is below 228.8 with a good RMS voltmeter. If it is, you are good to go. If it is not there are two ways to make it work. 1. Put a high wattage ballast resister in series with the supply voltage to drop the voltage to the motor within range of 187.2 to 228.8 volts. To determine the value of the resistor take the Horse Power of the motor and multiply it by 746. This will give the wattage of the resistor, use one at least 20% larger. Next take the Rated Load Amps (RLA) or Full Load Amps (FLA) of the motor and divide it into the difference between 230 (voltage supply) and the 208 (rated motor voltage), this will get you close to the resistance value of the Ballast resistor you need to use. So a 1/2 HP motor with a 1.2 RLA will require about a 18 ohm, 500 watt ballast resistor. This is not the recommended method, but will work. 2. Install a Buck & Boost transformer rate for the HP of the motor that will Buck the supply voltage for the motor down to 208 volts. This is the recommended way and the only way it should be done. Any good commercial electrical supply house can help you properly size the transformer that you will need.

Is DOL starter a star delta starter?

noComment:With DOL, the full line supply voltage is applied to the motor windings at starting. This is commonly used where the motor is not starting under load or under a heavy load.Star-Delta,In this case a reduced voltage is applied to the windings at starting and it's achieved since the phase voltage is a quotient Line voltage divided by 1.703. After the motor has attained speed, usually 3 seconds, the full line supply voltage is then applied to the motor windings.

Will a 3 phase motor work on grounded B phase?

If the motor is connected to an ungrounded delta supply service there will be no effect on the operation of the motor. If the motor is connected to a wye system supply service and the B phase grounds out, the motor's overload protection would take the motor off line from the electrical supply.

How does an electric car work?

An electric car gets energy from the battery which is pre-charged whatever power supply you decide whether it be from your own renewable energy sources or from a utility company. The electric car has five basic units, Battery, Battery-Charger, Voltage Controller, Motor, and drive train. Wheels are driven by the drive train which gets its mechanical energy from the motor the motor in return gets its electrical power from the battery through the voltage-controller. The voltage-controller controls the voltage the motor receives and hence the speed of the car.

Can you use a 9 V DC transformer to power a 3 V DC motor?

You should be aware that there is no such thing as a 'DC transformer'. What you are probably referring to is a DC power supply. The answer is no, you cannot use a 9V DC power supply to drive a 3V DC motor, as its voltage exceeds the rated voltage of the motor by a factor of 3, and the motor will likely burn out.

What is the running amps of a 45 kW motor?

To answer this question the motor's voltage must be stated and whether the supply voltage is single phase or three phase.

How many amps does a HP motor V 3 phase pull?

This depends on the supply voltage it is running on.

What does CMAP mean on EMG tests?

compound motor action potentialThis is an electrical potential evoked by electrically stimulating a motor nerve and recording the electrical response (change in voltage) from a muscle innervated by that nerve.

Why speed is decreased when field current increases in dc motor?

Because with more field, the armature produces the same voltage at less speed. The voltage generated by the motor must always be less than the supply voltage. A motor that is driven faster than it wants to go becomes a generator.

What would cause a meter to read negative voltage across a DC motor?

A DC motor generates power when it is rotating even when no supply is connected.