ZX54 DC resistance box (seven group switch) features:

The instrument adopts a switch power supply, which is particularly suitable for measuring inductive load resistance. It can compensate for the current inertia of large inductive devices during measurement, quickly reaching a stable value of the test current and shortening the testing time. It is an ideal product to replace single and double arm bridges. This instrument uses a microcontroller as the control core, with high automation and fast testing speed advantages. The LCD Chinese character display menu operation is extremely convenient to use.
1. Used for precise adjustment of resistors in DC circuits.
2. Resistance boxes with a calibration of less than 0.05% for the entire machine.
3. Use precision resistance boxes to calibrate portable DC single arm bridges, etc.
ZX54 DC resistance box (seven sets of switches)TECHNICAL INDEX
1. Measurement range; 0.01 to 111111.11 ohms.
2. When following the following usage conditions, the error of the resistance box will not exceed the basic error allowed in Table 1.
① The temperature of the surrounding air is 20 to ± 1 ℃, and the relative humidity is below 80%;

② The current is direct current;
③ The power shall not exceed the rated value.
3. The basic error of the resistance box is specified in Table 1;
Table 1

×10000 ×1000 ×100 ×10 ×1 ×0.1 ×0.01
±0.01$ ±0.01% ±0.01% ±0.05% ±0.2% ±1% ±5%

4. The insulation resistance between the internal circuit and the outer shell of the resistance box should not be less than 1000 megaohms, and the test voltage should be 500 volts.
5. The insulation strength between the resistance box circuit and the casing must be able to withstand the action of a sine wave of 2000 volts AC for one minute at a frequency of 50 cycles.
6. The maximum allowable current between each level of the resistance box should not exceed the specifications in Table 2.
Table 2

Magnification x 0.01 x 0.1 x 1 x 10 x 100 x 1000 x 10000
Allow current passing through 1 ampere, 1 ampere, 0.3 ampere, 0.1 ampere, 0.03 ampere, 0.01 ampere, 0.003 ampere

7. The external dimensions are 308 × 233 × 93 millimeters and the weight is about 4Kg.

an instruction manual:
1、 Structure of resistance box
A resistance box is a variable resistance measuring tool, whose resistance value can be changed in a certain step within a known range.
The resistance elements of the switch type DC resistance box are connected between each contact and fixed to each rotating contact, while the electric brush moves on the contact.
The resistor used in this type of resistance box is the resistance between the starting contact and the contact touched by the brush during use.