Coal Stacker communication

[shantanu@india]

Hi,
For those who are not familiar with stackers, these are electrohydraulic machines moving to and fro and transferring pulverized coal to a conveyor belt. The conveyor discharges the coal into the primary conveyor which feeds the boiler(power plamt etc.)
Some electrical interlocks are essential between the control system of the stacker and that of the conveyor. For example if the main conveyor trips due to overload, the stacker conveyor should also stop to prevent piling of coal on a idle conveyor.
The distance between the stacker and conveyor PLC's are about 500 meters with little obstruction but not line of sight. The working conditions are expectedly very bad.
What wireless module to use in this situation? Any suggestions would be gratefully accepted.

[top204]

I've used the E220 RF modules and they are inexpensive and give quite a long distance. They are also very easy to work with and just require a USART connection to setup their address and channels and power etc. Then the USART is used to transmit and receive the data.

They aren't very low power when not in use, at around 3ma to 6mA, but for the approx 100mA when transmitting at full power, they have quite a long range and come in various frequency ranges.

[shantanu@india]

Thanks Les.

[keytapper]

I had a different idea, the main conveyor belt may be used to drive the ancillary conveyors. So, every ancillary belt should use one wheel as a sensor and the sensor  might operate as on/off state or as linear speed sensor.
If the main conveyor is made of several units, then they may be subjected to the same condition.
Any stops on the main conveyor, by any chance, will be seen on each ancillary conveyor, even speed control may be applicable.

[trastikata]

LoRa modules are quite noise immune and the range is certainly covered even without LOS.

However as in any critical application I'd look for redundancy as well. 

[shantanu@india]

I had a different idea, the main conveyor belt may be used to drive the ancillary conveyors. So, every ancillary belt should use one wheel as a sensor and the sensor  might operate as on/off state or as linear speed sensor.
If the main conveyor is made of several units, then they may be subjected to the same condition.
Any stops on the main conveyor, by any chance, will be seen on each ancillary conveyor, even speed control may be applicable.

Your idea is absolutely spot on Keytapper and had been adapted in cascaded conveyor design for many decades. The speed detectors are called "Zero Speed Switch" and are interlocked with the preceding conveyor section. If the speed of any section falls below a certain limit, all the preceding sections trip in a cascading sequence.
I remember Bill3399 from the old forum who used to work in the mining sector. He would have been familiar with zero speed switches.

[joesaliba]

I had a different idea, the main conveyor belt may be used to drive the ancillary conveyors. So, every ancillary belt should use one wheel as a sensor and the sensor  might operate as on/off state or as linear speed sensor.
If the main conveyor is made of several units, then they may be subjected to the same condition.
Any stops on the main conveyor, by any chance, will be seen on each ancillary conveyor, even speed control may be applicable.

I used a similar system on a concrete batching plant. All I used was an off the shelf timer, a magnet, and a reed switch.

Every time the reed switch was ON, the timer was reset, if the reed switch was off for an x amount of time, the timer will open the circuit for the other conveyers.

I cannot remember if I did another timer just in case the magnet stopped in front of the reed switch.

This was way before I started PIC's:)
 Joe

[John Lawton]

You can probably get reed switches, but PICs....?

[Craig]

Hi shantanu

As mentioned by Trastikata I would Look at Lora with it's myriad of uses and robustness, I am currently using some modules from NiceRf with TCXO and they are working Brilliantly. https://www.nicerf.com/

Regards

Craig 

[shantanu@india]

Thanks Craig

[keytapper]

Your idea is absolutely spot on Keytapper and had been adapted in cascaded conveyor design for many decades. The speed detectors are called "Zero Speed Switch" and are interlocked with the preceding conveyor section

I never knew about these "zero switches" i thought that the sensing should be directly coupled on the belt surface,  any reason that stops/changes the belt motion will generate a feedback condition. Then these "zero switches' may be connected  wireless or wired to the control panel.