What I've done is -

1) set the sensor at 85% of normal running speed

2) use one sensor on the driving pulley and one on a driven pulley, then monitor the difference between them.

Best done with a mini PLC unit.

It worked OK! ■

I wouldn't like guarantee it, however once you have the kit installed you'll be able to find out EXACTLY what happens.

Let us know what you find. ■

A proper encoder design will include quadrature two track A;B square waves. Each track provides a leading and trailing edge pulse. Thus, with quadrature you have four signals. This allows filtration of spurious noise so the signal is only: A Leading-A Trailing; B Leading-B Trailing or A Leading-B Leading; A Trailing-B Trailing.

Our transducer does this and optically isolates against undesirable voltage potentials that plague instruments.

TYpical encoder pulse count is 500 ppr; 1000 ppr; 2000 ppr and 8000 ppr. The higher count may be due to mounting on the high speed shaft, or wish to have 1% accuracy at 1% speed, and 1% accuracy at 100% speed. How quick does the control need to be to regulate at all speeds, and the scan cycle of the PLC. If the encoder is mounted on a 100 hz pulley, then at 1000 ppr you have .1 megahertz or with quadrature you have 0.4 megahertz.

We design for PLC scan cycles of 10-20 ms and require 3 scan cycles before a decision is processed to eliminate bouncing contactors, electrical noise such as contractor closures, walky-talky pulses, et al. At least 5 pulses are needed to obtain a reasonably accurate speed reference, added to the scan and low speed

Some simple systems only count the high pulse on a sine wave. This type is not an accurate signal generator at low speed.

Belt elastic differential between drive and non-drive is much less than you 1-2%. 1% would give a motor torque differential between pulleys of 100%. Not desirable and not likely. Pulley lagging wear can result in 10-50% power differential, drive motors have between 1 and 2% electrical slip, and elastically, steel cord will have a fraction of 1% while fabric can approach 1% with the more flexible fabrics. ■

Glad to have been able to offer positive advice. ■

Dear Designer,

What is the difference between a driven and drive pulley?

Maybe its really a driven and non-drive or non-driven? ■

A drive pulley drives.

A driven pulley is driven.

E.g. consider a v-belt drive

The pulley mounted on the motor shaft is a drive pulley, while that mounted on the machine the the motor drives is a driven pulley.

At least that's the way it is in the land of the English language :-) ■

I do agree with your assessment. However, do you agree with mine, given conventional motor to drive pulley and driven pulley are one and the same? ■

Considering the specific case of a belt conveyor.

The driving pulley/pulleys are those that impart power and motion to the belt so that it can convey material, i.e. the pulley drives the belt.

The driven pulley/pulleys are those that rotate only because the belt is moving causing the rotation and imparting the necessary power to overcome the resistance to rotation however small that may be, i.e. the belt drives the pulley. ■

Yes, now I see. It is the non-driven pulley that is the driven pulley.

Gosh. ■