Partial voltage drops and partial clamp currents
Measurement of resistances and impedances in the system is part of essential maintenance. MI 3144 in combination with MI 3155 enables use of both current clamps and voltage clips, which enables precise measurements of partial impedances in the system. Very high measuring current up to 300 A provides very good resolution, immunity to noise in the system and repeatability of results. 4-wire method ensures excellent accuracy.
These features are a requirement for measuring components like fuse holders, cables, contacts, busbars or powerful switches. Their impedances are extremely low in the milliohm range.
The measurement is executed by first connecting the current clamps next to the element whose impedance shall be measured. They must be connected to the same leg of circuit, so that the same current is running through both. This way, the parallel legs of the circuit are excluded from the measurement.
A floating voltmeter with very high internal resistance is connected in parallel to the measured element. It doesn’t affect the measurement of current. This combination enables measuring precise values of current and voltage in an element or a leg of the circuit and impedance can be calculated with a high accuracy. Other parts of the same circuit do not influence the result.
MI 3144 supports a selection of iron or flex clamps for different current ranges. Iron clamps like A 1019 offer high resolution for low currents, even leakage. Flex clamps enable measurements of very high currents or conductors with very high cross-section. They can be rolled into multiple turns around the measured conductor to boost the signal and improve the result accuracy and resolution.
4-wire Kelvin connection is easily achieved using the large Kelvin crocodile clips. High isolating handles offer some safety for the user, but during work in vicinity of high voltage circuits personal protective equipment is mandatory. Four-wire type of connection with separated test crocodiles to eliminate serial resistances and bad connections. Test leads compensation is not needed.
Iron Clamps connected to an external output to eliminate parallel resistances and current paths where several circuits are connected to live network.
Flex Clamps connected to an external output for use on high current busbars and powerful conductors with large cross-section.