typically the ratio is on the current transformer
it will say something like 100:5 witch means 5a meter becomes 100A full scale
the 5 instead of a 1 gives you a hint about the capacity of the transformer
its 20:1 so you could use it to make a 1A meter into a 20A
but making a 10A meter into a 200A may lead to problems (accuracy or power)
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.
A current transformer works on the same principle as that of a simple transformer however it steps down the high current into a low level so that it can be measured using an ammeter of a suitable range. In some current transformers extra cores are provided. This is done in order to prevent the faulty currents i.e. the over currents, earth faults, differential protections. The extra cores of a C.T. gets saturated as soon as the faulty currents starts flowing and thereby does not harm the main core of the transformer and the ammeter connected. The C.T. is always connected in the line carrying current. It first steps down the current to a measureable form and further gives this current to the ammeter.
A shunt is connected in parallel with an ammeter. Any current applied to parallel devices will divide betwen them, so the ammeter will pass only a part of the total current.
if we take resistance in parallel with ammeter then the range of ammeter will change.
aryton shunt in a multirange ammeter is basically a bunch of resistors(shunt) connected together in parallel to the Dc ammeter and a selector switch in order to basically extend the range of the current...
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.
A current transformer works on the same principle as that of a simple transformer however it steps down the high current into a low level so that it can be measured using an ammeter of a suitable range. In some current transformers extra cores are provided. This is done in order to prevent the faulty currents i.e. the over currents, earth faults, differential protections. The extra cores of a C.T. gets saturated as soon as the faulty currents starts flowing and thereby does not harm the main core of the transformer and the ammeter connected. The C.T. is always connected in the line carrying current. It first steps down the current to a measureable form and further gives this current to the ammeter.
This can occur with a permanently installed, or clamp on, ammeter, when the secondary winding is not maintained in a shorted condition. This changes the mode of the current transformer from current reduction to voltage increase, often of a substantial, lethal value.
HOW TO CONNECT AN AMMETER Always connect an ammeter in SERIES in a circuit. Always ensure that the ammeter has a higher reading range than the expected current load, including start-up spikes. An ammeter expected to read a steady current of 13A should have a max range of 20A.
A shunt is connected in parallel with an ammeter. Any current applied to parallel devices will divide betwen them, so the ammeter will pass only a part of the total current.
if we take resistance in parallel with ammeter then the range of ammeter will change.
These are used with low range ammeters to measure current in HVAC 's where direct connection of instruments is impratical. They not only insulate the instruments from HV lines but also step down current in a known ratio. ( i .e . ) Iline =(I1 \I2) * Ammeter Reading where Iline = Line Current I1 \I2 = Current Ratio
To increase the range of an ammeter, you connect a very low impedance resistor in parallel with the ammeter.
The voltage remains the same across the circuit as it is a parallel connection. So, the current across the upper half of the circuit where the ammeter is connected is calculated as I = V/R = 12.04 (total voltage)/12 (Resistance R1) = 1 A. Hence, the ammeter will read 1 A.
aryton shunt in a multirange ammeter is basically a bunch of resistors(shunt) connected together in parallel to the Dc ammeter and a selector switch in order to basically extend the range of the current...
An ammeter, either shunt or inductive. A shunt is an inline resistor of a small, known resistance. Knowing the resistance and the voltage one can calculate the amperage by Ohms law, I=V/R. An inductive, or clamp on ammeter measures the magnetic field and using more complex calculations displays the current, typically on a digital display.
2000ma is equal to 2 amps. Set you meter to a current range ABOVE 2 amps.