Q144-BC Q96-BC Q72-BC Q48-BC Ammeter DC

Q144-BC Q96-BC Q72-BC Q48-BC Ammeter DC

Overview of Q144-BC Q96-BC Q72-BC Q48-BC Ammeter DC

In the magnetoelectric measuring mechanism, because the wire of the movable coil is very thin, and the current also passes through the hairspring, the allowable current is very small, about a few microamps to hundreds of microamps, so its practical value is very small. According to the principle of shunt function of parallel circuit, shunt resistance must be added to measure large current in practice. Therefore, DC ammeter is usually composed of magnetoelectric measuring mechanism and shunt resistance in parallel. Because magnetoelectric ammeter can only measure DC current, it is also called DC ammeter.

The selection of common DC ammeter is the same as that of DC voltmeter. If a shunt is used, the shunt must be used together with the ammeter. The wiring of the DC ammeter has polarity. The positive pole of the power supply (the pole of current flowing out) must be connected to the + end of the ammeter, and the - end of the ammeter must be connected to the negative pole of the power supply (the pole of current flowing in). When the polarity of the DC meter is not clear, the DC voltage regulator can be used to reduce the voltage and current for temporary access. When the pointer is biased correctly, the wiring is correct. When the bias is opposite, the positive and negative poles (+, -) can be adjusted and connected. Grounding of DC ammeter

DC ammeter can be divided into ammeter, milliammeter and micro ammeter according to the range, which are represented by symbols a, Ma and UA respectively.

Main parameters of Q144-BC Q96-BC Q72-BC Q48-BC Ammeter DC

(1) Range: that is, the current value at full scale, expressed in IM. The DC ammeter commonly used in the laboratory sometimes has several ranges to choose from. Correspondingly, there are more than two terminals, one is the common terminal, and the other terminals are marked with the corresponding range:

(2) Internal resistance: the internal resistance of the ammeter is very small to reduce the voltage drop on the ammeter during measurement.

(3) Accuracy grade: according to the national standard, the ammeter is generally divided into 7 Accuracy grades, and the measurement results of ammeters with different Accuracy grades have different accuracy.

Select 

The following points should be paid attention to when selecting and using DC ammeter.

① Type selection. In the measurement of DC current, the instrument of magnetoelectric measuring mechanism is mainly used.

② Selection of accuracy. The accuracy of the instrument should not be too high, but should proceed from the reality of the measurement requirements. Generally, level 0.1 and 0.2 instruments are selected as standard meters; Class 0.2 instruments are selected as measuring instruments; Class 0.5 and 1.0 instruments are selected for laboratory measurement; Instruments below level 1.5 are generally selected as engineering survey.

③ Range selection. Correctly estimate the value range to be measured and reasonably select the range. Generally, the indication of the instrument to be measured is greater than 2 / 3 of the maximum range of the instrument, but cannot exceed its maximum range.

④ Selection of internal resistance. The internal resistance of the instrument reflects the power loss of the instrument itself; In order to reduce the measurement error, the ammeter with the smallest internal resistance should be selected when measuring the current.

⑤ Correct wiring. When measuring current, the ammeter shall be connected in series with the circuit under test; When measuring DC current, pay attention to the polarity of the instrument and make the polarity of the instrument consistent with the measured polarity.

⑥ Expansion of range. When the measured in the circuit exceeds the range of the instrument, the external shunt or voltage divider can be used, but it should be noted that its accuracy level should be consistent with the accuracy level of the instrument.

In addition, it should also be noted that the service environment of the instrument should meet the requirements and be far away from the external magnetic field. The pointer shall be at the zero position before use, and the line of sight shall be perpendicular to the plane of the scale when reading.