GT87-2 DC potentiometer instruction manual I. Overview The GT87-2 DC potentiometer is suitable for teaching in the laboratory and can be used directly to measure DC potential. Second, the main technical data 1. Accuracy level: 0.5 2. Basic error limit: Elim=±(2×10-3+5×10-3X) V where: Elim—allowable limit value of error (V), X—measurement disk value 3. Measurement range The upper limit of the measurement of the potentiometer is 1.600V, and the minimum division is 1mV. 4. Working current The potentiometer is a low-resistance potentiometer with an operating current of 5 mA, which is equivalent to a 200 Ω resistor per volt. 5, the reference conditions of the basic error ambient temperature 20 ± 5 ° C, relative humidity 40% -80%. 6. Variation limit When the potentiometer is under the reference condition and the single influence quantity changes, the resulting variation is as follows: Amount of influence Grade index (%) Nominal use limit Allow variation Ambient temperature 0.5 20±10°C 50% Relative humidity 25% and 90% 30% 7, high pressure test In the range of ambient temperature 15-35 ° C, relative humidity 45%-75%, the dielectric strength between the conductive part of the potentiometer and the outer casing should be able to withstand the frequency between 45-65 Hz, the actual sine wave test voltage 1KV (root mean square value) lasted 1 minute of the test without breakdown. 8, insulation resistance The insulation resistance between the conductive part of the potentiometer and the outer casing shall be not less than 100 MΩ at an ambient temperature of 15-35 ° C and a relative temperature of 45% to 75%. Third, the principle 1, the basic working principle EN—standard battery EX—measured electromotive force K-switch G-galvanometer E—working power RX—measured electromotive force compensation resistor RN—standard battery compensation resistor RP—working current regulation rheostat The principle of the potentiometer is based on the compensation method to compare the measured electromotive force with the standard electromotive force. The principle is shown in Figure 1. Before the measurement, the potentiometer should first correct the working current. According to Figure 1, put K in "EN" (or complete by wire), adjust the RP to make the galvanometer zero, then: EN=IRN ............(1) From (1): ………(2) Where I is the current flowing through RN and RX, which is the operating current of the potentiometer. After the working current is adjusted, set the transfer switch to EX (or complete by wire), adjust RX to make the galvanometer zero. EX=IRX (3) The working current I here is the I value in (2), so it is available. (4) The principle circuit of GT87-2 DC potentiometer is shown in Figure 2. Fourth, the structure 1. The panel layout of the instrument is shown in Figure 3. In the picture: (1) B+ connected DC regulated power supply positive terminal (2) ×1, ×0.01 with DC voltage regulator adjustable power supply negative end (3) The two discs are measuring disc adjustment knobs. (4) E+ E- connected to the measured potential Five, instructions for use 1, preparation before use: 0 ~ 2 volt DC regulated power supply, pointer galvanometer, BC9 standard battery, ZX21a resistance box 2. Measuring the electromotive force (voltage) method below 1.600V: (1) Adjust the operating current Before adjusting the working current, the standard battery and electromotive force should be considered to be affected by temperature. At a certain temperature, the standard battery electromotive force can be calculated by the following formula, and the calculated number of digits is 0.00001V. Et=E20-0.0000406(t-20)-0.00000095(t-20)2 In the formula: Et is the electromotive force of the standard battery at t °C. E20 is the electromotive force of the standard battery at +20 °C. T is the indoor ambient temperature during measurement After calculating the value of Et, the potential difference meter is adjusted to the corresponding value. For example, when calculating the temperature of t, the electromotive force of the standard battery is 1.01860V, and the DC adjustable power supply is connected to the B+ and ×1 buttons, and the BC9 standard is adopted. Battery, galvanometer string into the E + E- terminal, adjust the measurement disk reading to 1.0186 volts, then adjust the power supply to make the galvanometer zero, then the working current is adjusted. (2) Measuring unknown electromotive force After the working current is adjusted, the power supply voltage can not be moved any more. The measured potential is connected to the E+E terminal. At this time, the galvanometer pointer points to one side, and the measuring dial knob can be adjusted to make the galvanometer pointer zero. The sum of the measured values ​​of the two measuring discs is the value of the measured potential. After multiple measurements, the working current should be calibrated to make the measurement accurate. 6. Maintenance and warranty period 1. The potentiometer should be stored in an indoor temperature +10 ° C ~ 35 ° C, relative humidity ≤ 75% indoors, indoors contain impurities and gases that can cause corrosion. 2. If the user complies with the use and storage conditions stipulated by the manufacturer, and the product is damaged or cannot work normally due to poor manufacturing quality within one year from the date of delivery, the manufacturer is responsible for repairing the product for free. Seven, complete set The documents supplied with the product are: a, product manual b, certificate c, packing list Nursing Bed,Clinical Caring Bed,Wooden Healthcare Bed,Wooden Nursing Medical Bed Jiangmen Jia Mei Medical Products Co.,Ltd. , https://www.jiamei-medical.com figure 2
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