Torque Meter Frequently Asked Questions

Question number FAQ-1268

Wiring work and noise.

When noise is superimposed on the torque signal, for example;

The display fluctuates greatly despite being in a no-load condition.
Despite having a constant rotation and a constant load torque, the torque display and the analog output voltage fluctuate significantly.
When the power to the drive motor and load device is turned off, the display stabilizes at zero, but when this power is turned on, the variation increases significantly.

Symptoms such as these may appear. It is necessary to take preventive measures against such noise during the installation wiring in advance. Below is an excerpt from the manual of the TS-3200 model display, titled 'Wiring Precautions for Torque Meters.' Please refer to it.

In recent years, there has been an increase in the use of inverter motors and testing devices that measure inverter motors. Inverters generate noise due to their operating principles, which can affect adjacent equipment, including torque meters. The degree of influence is related to the amount of noise generated by the inverter, the installation conditions of signal lines, the installation state, and the distance between the equipment and the inverter, and it cannot be uniformly determined. However, by referring to the precautions below regarding wiring installation in advance, troubles caused by noise generated by the inverter can be reduced. Additionally, we request that the following be referenced for construction work in cases other than inverter noise.

Please implement radiated noise countermeasures on the inverter unit side.
Separate the main circuit input and output wires of the inverter from the power and signal wires of the torque meter.
The separation distance should be at least 300mm, and if separation is difficult, use a metal conduit for the power and signal wires of the torque meter, grounding one side of the metal part to the earth.
Always use the dedicated cable that comes with the detector for the torque signal line.
The frame for installing the torque detector is grounded to the earth.
For the TS series display, if the power plug is 3P, always use all 3P, and
be sure to connect the ground terminal to the earth ground. If it is 2P, use the
case ground terminal on the back of the TS series display to connect to the earth ground.
The power supply for the TS series display device should be on a separate system from the inverter power supply. If this is not possible, a noise-cut transformer should be installed.
Implement noise reduction measures as instructed by the inverter manufacturer.

Last updated: 2008-09-24