Torque Meter Frequently Asked Questions

The current of the motor under test is measured by detecting the voltage across a 0.1Ω shunt resistor, as shown in Figure 1.
The shunt resistor reduces the voltage supplied to the motor under test, so a SENSING terminal is provided and switched by a relay to compensate for this. When the MOTER ON operation is performed, this relay switches ON, but it remains open for a very short time. Depending on the DC power supply, this open state of the SENSING terminal may generate a high voltage in the form of a spark as shown in Figure 2, activating the alarm protection.

<Countermeasures>
Insert the two thick solid R resistors, C1, and C2 shown in Figure 1 so that the initial voltage remains applied to the SENSING terminal even when the circuit is open. The values below are for reference only. In practice, select components such that the spark shown in Figure 2 is within a voltage range that will not adversely affect the motor under test. Pay attention to the polarity when installing the capacitors. Please also confirm with the DC power supply manufacturer.

R: 100 Ω,
C1: 1000μF / Ensure sufficient voltage rating to accommodate the maximum DC power supply (50V to 100V).
C2: 0.1μF ceramic capacitor / Add this if C1 cannot cut off the whisker-like sparks.

< Figure 1 >

< Figure 2 >