Torque Meter Frequently Asked Questions

The current of the test motor is detected from the voltage across a 0.1Ω shunt resistor as shown in Figure 1.
Since the voltage supplied to the test motor is reduced by the shunt resistor, a SENSING terminal is provided and switched by a relay to compensate for this. This relay is switched ON during the MOTOR ON operation, but it remains in an open state for a very short time. Depending on the DC power supply, a spark-like high voltage as shown in Figure 2 may occur due to the open state of this SENSING terminal, triggering the alarm protection.

Countermeasures
Even when opened, insert R×2 pieces and C1, C2 as shown in the solid line in Figure 1 to ensure that the initial voltage is applied to the SENSING terminal. The following are reference values. In practice, please select components that keep the spark in Figure 2 within a voltage that does not adversely affect the test motor. Please pay attention to the polarity when installing the capacitors. Also, please confirm with the DC power supply manufacturer.

R: 100 Ω,
C1: 1000μF / Please ensure the voltage rating is above the maximum DC power supply (50V–100V)
C2: 0.1μF ceramic capacitor / Add this if the whisker-like spark cannot be cut with C1.

< Figure 1 >

< Figure 2 >