Cable fault testerVerification steps for millivolt transmitters

1) Cable fault wiring. Select the temperature compensation resistor Rcu according to the type of thermocouple.
If the range is less than lomv and the R value in the short-circuit feedback loop is greater than lomv, then connect Rm. When the zero transition range is small, connect R: d in parallel with w:; When the zero migration range is moderate, no assistance will be provided; When the zero migration range is greater than 50mv, connect R: d in series with wa. Then, press the verification circuit. Rc u should be short circuited during verification.
2)Cable fault testerCheck the current on the bridge. Adjust w: Make the bridge current 1mA. Insert an ammeter between terminals ④ and ⑥ to check if it is 1mA.
3)Cable fault testerOpen loop amplification factor check and reverse signal check. Adjust WL to zero the feedback voltage. Due to the potential having a certain initial resistance, the feedback voltage may not be zero. When reaching this point, a short circuit can be used to short-circuit R2 and Rm, causing the entire machine to be in an open-loop state. Then input a signal to set the output current to 0.5-1mA, and add a 50KVDC signal. If the output current is greater than 10mA, it is considered qualified and reaches 1; To reach 10mA, wd needs to be adjusted to -60mv.
If it is an automatic adjustment system, the regulator should be switched to manual operation, and then the "work one check" switch of the cable fault tester should be set to the check mode. Non automatic adjustment systems can directly set the toggle switch to the inspection mode. If the output current is any value between 4-6mA, it indicates that the cable fault tester is working properly.
When the temperature sensing element is a thermocouple and needs to be verified on site, a portable cable fault tester can be used instead of the thermocouple to send the m number and check whether its output current is correct. At this time, the temperature compensation resistor should be short circuited. Then, the military point, range, and accuracy can be verified using indoor calibration methods.
If the temperature sensing element is a thermal resistor, a portable resistance box can be used instead of a temperature measuring resistor. Check and adjust the zero point, cable fault range, and accuracy according to the resistance values given on the resistance box for each temperature point.