Temperature sensor: NTC 25ºC=10K B3435 ±1% what cable?

[ericmark]

I remember when doing stress relief we used special compensating cable between the sensor and the controller. Do these sensors the NTC 25ºC=10K B3435 ±1% quote from operation instructions need special cable or can I use simple bell wire, and same with plugs and sockets do I need special or will anything do?

Also running two controllers on the same batch of beer one for heating and one for cooling, can I use same sensor for both or do I need one each? If one each can a common one cable so using three core rather than 4 core?

I use them to brew beer, in the summer months one controller a STC 1000 controls heating and another a MH1210A the cooling which gives me three differentials so I get.

18ºC heating starts.
18.3ºC heating stops.
20.0ºC cooling starts.
20.1ºC cooling stops.
With a 15 minute delay before cooling starts.

I can't use a single controller as with the STC1000 the 0.3ºC differential is universal so measuring the fermentor (and I am not really interested what the temperature of the freezers air is.) the fermentor drops more that 0.3ºC each time the motor starts, so heating then comes on even in the hot days. So I have to use both controllers, I would like to reconfigure them all into one box, although the STC1000 has two relays in real terms can't use both so may as well combine both units together. Would like to extend cables so I can monitor from computer room. Hence the question.

 

[bernardgreen]

NTC is ( normally ) a Negative Temperature Coefficient thermistor and the resistance varies with temperature. Any cable can be used provided the resistance of the cable is less than 1% of the resistance of the sensor if 1% temperature measurement accuracy is needed.

Can one thermistor sensor serve two controllers. Very unlikely as each controller will be putting a small current through the thermistor and measuring the voltage across the thermistor to obtain the resistance. With twice the current the voltage across the thermistor will be doubled and the temperature measurement will not not be correct.

For similar reasons a pair of sensors should not share a common connection to their two controllers.

For a short run 2 pair telphone cable will allow reasonably accurate measurements to be made.

 

[Jackrae]

Compensating leads are only required when using thermocouples to prevent intermediate junctions causing measurement errors. For a 10k NTC, bell wire will suffice (current flow is usually less than 1mA) as will simple connectors.

 

[Gteuk]

Bell Wire is sufficient upto 20m on most 10K sensors upto about 50m on PT1000 series.

 

[Spark123]

A few ohms of wire isn't going to make much difference to a 10K detector.

 

[securespark]

I think you should use a length of 10 milli SWA just to be on the safe side.

 

[ericmark]

Thank you for your replies, it seems a simple bell wire is good enough. as to when I rewire and modify my existing unit not sure, I need to complete the brew being done at the moment. I will raise a glass to all the replies.

 

[securespark]

SOMETHING STRANGE GOING ON ALERT......

I didn't post that...

 

[Echo the husky]

Trying to increase your post count?!

 

[securespark]

I need to reduce it...!