Ammeter 99T1-A
The 99T1 ammeter is a commonly used pointer ammeter, suitable for installation on display panels and large switch boards of various control and distribution systems to indicate relevant electrical parameters such as AC/DC current, voltage, power factor, power, synchronous value, frequency, unfolding voltage, and overload current.
The 99T1 ammeter is commonly used as a pointer ammeter. Convenient to observe the specific magnitude of the current.
Application scope
Widely used in the following industries: power plants, distribution facilities, mechanical equipment, ships, aviation, transformers, etc
International standard
99T1 ammeter according to internationally recognized pointer ammeter specifications and dimensions:
Composition structure
Composed of a fixed magnetic circuit system and movable parts. The magnetic circuit system of the instrument includes a permanent magnet 1, pole palms 2 fixed at the two poles of the magnet, and a cylindrical iron core 3 located between the two pole palms. The cylindrical iron core is fixed on the instrument bracket to reduce magnetic resistance and generate a uniform radiating magnetic field in the air gap between the pole palm and the iron core. When the movable coil 4 in this magnetic field deflects around the axis of rotation, the magnetic fields on the two effective sides are always equal in magnitude and perpendicular to each other. The movable coil is wound around an aluminum frame. The shaft is divided into two parts, front and rear. One end of each half shaft is fixed on the aluminum frame of the moving coil, and the other end is supported in the bearing through the shaft tip. There is also a pointer installed on the front half shaft, which is used to indicate the magnitude of the measured electricity when the movable part deflects.
Structural characteristics
1: (Instrument) measuring circuit
The internal circuit part of the electricity meter and its accessories, including the interconnected wires (if any). Powered by current or voltage, one or both of which are the main factors determining the measured indicator value. (One of the current or voltage may be the measured itself)
2 Current Circuit
A measuring circuit whose current is the main factor determining the measured indicator value.
Note: The current passing through the current line can be directly the measured current, or supplied by an external current transformer, drawn out by an external shunt, and proportional to the measured current.
3 Voltage Lines
A measurement circuit in which the voltage applied is the main factor determining the measured indicator value.
Note: The voltage applied to the voltage line can be the measured voltage, or the voltage supplied by an external voltage transformer or voltage divider, or the voltage proportional to the measured voltage drawn from an external series resistor (impedance).
4 External measurement lines
The external circuit part of the instrument, from which the measured value can be obtained
5 auxiliary lines
Necessary for instrument operation, measuring circuits outside of the circuit.
6 Auxiliary power supply
Auxiliary circuit for supplying electrical energy
7 measuring components
Some component combinations of measuring elements. They can cause the movable part to produce motion related to the measured object under the action of the measured object.
8 movable parts
The movable components of the measuring element.
9 indicator device
The component in the measuring instrument that displays the measured value.
10 indicator
A component that uses a scale to indicate the position of a movable part.
11: Scale ruler
A series of markers and numbers, combined with indicators, can be used to obtain the measured value.
12 division line
The markings on the dial divide the scale into appropriate intervals to determine the position of the indicator.
13 Zero Dividing Line
The zero digit mark on the dial.
14 divisions
The distance between any two adjacent dividing lines.
15 degree digits
A series of numbers combined with the dividing line.
16 Mechanical Zero Position
The equilibrium position of the indicator after the measuring element of the mechanical control is powered off. This position can coincide with or not coincide with the zero division line.
In instruments with mechanical compression zero position, the mechanical zero position does not correspond to the dividing line.
In instruments without significant mechanical reaction forces, the mechanical zero position is uncertain.
Accuracy
The precision of instruments is called accuracy, also known as precision. Precision and error can be said to be twin brothers, because the existence of error gives rise to the concept of precision. In short, instrument accuracy refers to the degree to which the measured value of the instrument is close to the true value, usually expressed as relative percentage error (also known as relative conversion error).
Variation
Variation refers to the maximum difference between the indicated values of an instrument when the measured variable (which can be understood as the input signal) reaches the same value from different directions multiple times. In other words, the variation of the measured parameter from small to large (positive characteristic) and from large to small (reverse characteristic) is the degree to which the measured parameter does not match under constant external conditions. The difference between the two is called instrument variation
Sensitivity
Sensitivity refers to the sensitivity of an instrument to changes in the measured parameter, or in other words, the ability to respond to changes in the measured quantity. It is the ratio of the output change increment to the input change increment in steady state. Sensitivity is sometimes also known as the "amplification ratio" and is the slope of each point on the tangent line of the instrument's static characteristics. Increasing the amplification factor can improve the sensitivity of the instrument. Simply increasing the sensitivity does not change the basic performance of the instrument, that is, the accuracy of the instrument does not improve. On the contrary, sometimes oscillation phenomena may occur, causing unstable output. The sensitivity of the instrument should be maintained at an appropriate level.
