PC57 DC Resistance Measuring Instrument

PC57 DC Resistance Measuring InstrumentIt is a specialized instrument for measuring the direct current resistance of wire and cable conductors. The technical performance of the instrument should fully meet the technical requirements of the measuring equipment in GB/T3048.4 conductor direct current resistance test, with fast, accurate measurement, stable reading, and easy use. It is an updated product of QJ57 and other double arm electric bridges. Compared with similar digital micro ohmmeters, it has the following characteristics:

1.1 High sensitivity and high resolution. The resolution of this instrument in the 2m Ω range is 0 1 μ Ω (10-7 Ω), which is 10 times higher than the highest resolution of existing digital micro ohmmeters measuring current of 1A. Adopting a highly sensitive and low-noise nanovolt amplifier with a voltage sensitivity of 100nV (0.1 μ V), it can measure copper wires with a cross-sectional area of 100mm2 and a length of 1 meter, ensuring 4 effective readings. It is particularly suitable for measuring larger cross-sectional wires and ultra small cross-sectional fine wires.

1.2 Multi current measurement function. The various ranges of the DC resistance measuring instrument are set with different measurement currents to choose from, which are indicated on the instrument panel. This performance overcomes the shortcomings of current measurement that cannot be adjusted by digital meters and some bridges (such as QJ57), and the heating of the measured conductor caused by excessive current in certain gears. In order to achieve multi current measurement, a digital proportional measurement circuit is used, which works similarly to a bridge. Unlike the commonly used constant current source voltmeter method for digital micro ohmmeters, the final expression of the reading of this instrument is independent of the measured current, greatly reducing the accuracy requirements for the constant current source while improving the accuracy and stability of the instrument measurement.

1.3 Reverse current measurement function. According to Article 5.5 of GB/T 3048.5, when the resistance of the sample is less than 0.1 Ω, the current should be measured again in reverse and the arithmetic mean should be taken. In the bridge method, this function is achieved by switching the external commutation switch, while digital micro ohmmeters usually do not allow current reversal and cannot achieve the standard operation requirements. Adopting a specially designed bidirectional current protection circuit, it allows for reverse current measurement and current commutation operation through panel switches, which is simple to operate and easy to use.

1.4 Dual use of AC and DC, easy to use.PC57 DC Resistance Measuring InstrumentFor portable structures, when measuring coiled cables in the workshop or field, the machine is equipped with a large capacity lithium battery for power supply, and the panel is equipped with a power display to timely display the current power level. AC power supply can be used for fixed occasions.

1.5 has a high cost performance ratio and a wide range of applications. While achieving the above-mentioned multifunctionality and high performance, its price is only a fraction of that of similar digital low resistance meters with the same technical indicators (0.1 μ Ω resolution, 0.05 level measurement accuracy). It is currently a low resistance measuring instrument on the market, especially suitable for medium and small wire and cable factories, enameled wire production factories for conductor resistance testing. As an updated product of various electric bridges such as QJ23, QJ44, QJ57, it is also suitable for the power sector to quickly measure the DC resistance of large transformers, generators, and motors, switch contact resistance, precision measurement, and calibration of various shunts.