0
What are the disadvantages of shunt for measuring high current?
Wiki User
∙ 11y ago
When shunts are used in high current measurements, that actual current reading is "extrapolated"(multiplied by a factor then expressed) and variances in shunt tolerance may cause mistaken and less than accurate measurements.
Wiki User
∙ 11y ago
Add your answer:
Earn +20 pts
What is shunt conductance?
A low-resistance connection between two points in an electric circuit that forms an alternative path for a portion of the current. Also called bypass. Conductance of a shunt is high as the resistance is low.
What field setting for a dc shunt motor wired in series on high voltage?
A shunt dc motor has quite different characteristics from a series motor. Wired in series, the same current passes through the armature and the field winding and it is most unlikely that a shunt motor would have a field winding that is suitable for this. Therefore a shunt motor cannot be wired as a series motor in general because its field winding is designed for only a small current.
What happen when a DC shunt motor is connected to ac supply?
If it is a series motor it may still work. If it is a shunt motor it will not work , it will produce a humming noise and get heated. The shunt fields normally have high reactance so the field current will be drastically reduced, which may not be able to create the requisite torque.
What is a disadvantages DOL or direct online starter?
it can not be use for heavy duty motors as well as it requires a high starting current.
How do you increase current capacity of an ammeter?
In measuring high AC currents a current transformer with a suitable rating say 100/5 or 1000/5 are used. The secondary current is usually 5 amps when the fulload current of 100 or 1000 as the case may be is flowing in the mains. It is the univerasl practice to use CT's for measurement of AC currents. In DC circuits the transformer method will not work, so to increase the current that you can measure you can allow a known amount of current to bypass the ammeter and recalibrate the ammeter. In other words, put a shunt in parallel with the ammeter.
Why shunt resistance is connected in the parallel?
Shunt means parallel only..................
What would be the shunt field current of your motor if the shunt field winding is excited by?
It could be anything, it depends on the design of the motor and whether it is a high-power or a low-power motor.
Why shunt field resistance is high incase of dc shunt motor?
Back emf is proportional to the flux in the field winding.Flux in the field winding is proportional to the mmf in the winding.mmf = current passing through the winding * no of turns in the windingTo attain the required mmf we can use more current and less turns ( or ) less current and more turns .As the power loss in the field winding is considered it isPower loss = Square of voltage / resistanceAs the voltage is constant for a high resistance it is possible to have less losses. So we prefer for high shunt field resistance.As the field resistance is high current is less , so no of turns in the shunt field will be more to attain the required mmf.Answer'Shunt' is an archaic term for 'parallel', so the shunt winding is in parallel with the supply voltage which means its resistance must be relatively high to limit the current passing through it.Incidentally, the back-emf. is not proportional to the flux, but to the rate of change of flux.
What is shunt conductance?
A low-resistance connection between two points in an electric circuit that forms an alternative path for a portion of the current. Also called bypass. Conductance of a shunt is high as the resistance is low.
How do you find out the total current in PCB?
a: usually taking the high side of the buss or the return and measuring the current
What field setting for a dc shunt motor wired in series on high voltage?
A shunt dc motor has quite different characteristics from a series motor. Wired in series, the same current passes through the armature and the field winding and it is most unlikely that a shunt motor would have a field winding that is suitable for this. Therefore a shunt motor cannot be wired as a series motor in general because its field winding is designed for only a small current.
What is constantan wire used for?
In essence it is used in applications where it is important that the resistance of a length of contantan wire doesn't change with temperature. As a student the only time I've ever needed this feature is in experiments involving measuring resistance. A use for constantan wire is in DC Current Shunts. This is a precision low value resistance placed in series with the load in a direct current circuit that is carrying high current. By measuring voltage drop across the shunt, we can measure the current. In this application it is important that the resistance of the shunt does not vary with temperature (the shunt will heat up under full load) otherwise the accuracy of the current reading is compromised. Typically the resistance of the shunt is set to give 60 millivolt voltage drop across it at full current.
What happen when a DC shunt motor is connected to ac supply?
If it is a series motor it may still work. If it is a shunt motor it will not work , it will produce a humming noise and get heated. The shunt fields normally have high reactance so the field current will be drastically reduced, which may not be able to create the requisite torque.
What is the function of a summation current transformer?
Current transformers are used to measure electric currents. When current in a circuit is too high to directly apply to measuring instruments, a current transformer produces a reduced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments.
What is the function of shunt reator?
it is electrical device connected with high voltage current grids in order to protect the system from sudden drop or sudden change is voltage.
What is a disadvantages DOL or direct online starter?
it can not be use for heavy duty motors as well as it requires a high starting current.
Why shouldn't ammeter be connected in parallel?
A: An ammeter actually is a voltmeter measuring the voltage drop across a very small shunt resistance. They can measure AC or DC, make sure the meter is rated for the anticipated current, and always connect in series.
