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Junior01
I need to measure current in DC system. I have circuit breaker (125A), so 150A shunt is selected. On that shunt ammeter is connected. But that ammeter has 60mV, scale 0-150A. What does this 60mV means on ammeter? Is it correct?
A shunt is a resistor that causes a small voltage drop. This voltage drop is mVolt is proportional with the current in ampère that goes through the resistor
When you select a shunt, there is a multiplying factor for that shunt which gives you the actual value of the current. If your ammeter's full-scale deflection is 50A and you have extended its range to 150A (using shunt), multiplying factor would be 3. This means when your meter is showing 50A (full scale deflection), the actual current is 150A.Junior01 said:So, how my instrument will show on scale 150A, if measuring range is up to 50A.
Direct measuring ranges:
I = 40µA...25A,
U = 60mV...1000V,
Measuring ranges with external shunts: I = 1A...15kA
A shunt is a low-resistance device that is placed in series with a load in a DC circuit. It is used to measure the current flowing through the circuit by creating a small voltage drop that can be measured and converted to a current value using Ohm's law.
The value of a shunt is selected based on the maximum expected current in the circuit. It should be low enough to minimize the voltage drop, but high enough to prevent overheating. A good rule of thumb is to select a shunt with a resistance that is 1/1000th of the maximum current in the circuit.
The accuracy of current measurement using a shunt can be affected by factors such as shunt resistance, temperature, and placement in the circuit. A higher shunt resistance can result in a larger voltage drop and a less accurate measurement. Temperature can also affect the shunt's resistance, so it is important to select shunts with a low temperature coefficient. Additionally, the shunt should be placed in a location where it will not be affected by stray magnetic fields or other sources of interference.
To ensure proper shunt selection, it is important to carefully calculate the expected current in the circuit and select a shunt with an appropriate resistance value. It is also important to consider the temperature coefficient and placement of the shunt to minimize any sources of error. Additionally, regularly calibrating the shunt and using high-quality equipment can help ensure accurate current measurement.
No, a shunt is only suitable for DC current measurement. This is because AC current is constantly changing direction, which can cause errors in the measurement. For AC current measurement, other devices such as current transformers or Hall effect sensors should be used.