Help with electric furnace controller

[Dallon Penney]

Hello. I have built an electric tube furnace using nichrome wire, an AC contactor, and an Auber Instruments SYL-2342P PID controller. I have the basics of programming it figured out but the furnace can never get above 1525 F before the controller switches to "stop" mode. Here is my program:

C01->50

t01-> 90

C02-> 1825

t02-> 15

C03-> 1825

t03-> -121

The furnace heats up no faster than about 1-2 F per 5 seconds. What am I doing wrong? Is there a setting that is triggering the shut-off prematurely? Any help would be appreciated.

[Charles dP]

Hi Dallon. Unfortunately I can’t help and I guess a lot of people are kinda busy with Christmas. Perhaps @timgunn or someone else who knows about these things might stop by. Have you contacted Auber directly? I seem to recall someone saying they are quite helpful with technical enquires. 

Edited December 25, 2020 by Charles dP

[dragoncutlery]

i had an issue getting above some temp with mine i called auber and they were able to talk me threw it in a few minutes as for the slow heat up that would be the element unless the contactor is turning on and off constantly on heat up also theses work better with solid state relays than contactors the cycle rate is kinda hi when it gets going

[timgunn]

I'm not familiar with that controller.

 

Looking at the manual online, it appears times are in minutes?

 

From 50 to 1825 degrees is 1775 degrees of temperature change.

 

90 minutes is 5400 seconds.

 

1775/5400 is 0.33 degrees/second

 

1.65 degrees every 5 seconds, so your 1-2 deg per 5 sec seems about right to me?

 

I'll try to look at it again when there's a higher concentration of blood in my alcohol stream, and see if I can work out why it's going to "stop".

[timgunn]

What is the actual time from start to stop?

 

Is it 105 minutes?

 

It may be that you have put in too simple a program.

 

If you have a system that will reach 1825 degrees from a starting temperature of 50 degrees in 90 minutes under full power, the first part of the Temperature/time curve will be very steep. It will tail off as the temperature gets higher. 937.5 degrees (the half-way temperature) might well be reached within 5-10 minutes, leaving 80-85 minutes to achieve the other 887.5 degrees. 

 

If you slow down the time to 937 degrees with the first 45 minutes of the 90-minute ramp, you will only have 45 minutes of your 90-minute ramp left to get from 937 deg to 1825 deg, which takes 80-85 minutes at full power. You will not be able to reach the setpoint in the time you have allowed. You will probably still be way short of 1825 deg when the soak times out.

 

I'd try 

C01    50

T01     5

C02    1825

T02     100

C03    1825

T03     -121

 

It'll still give the 105 minute cycle, but should (if I'm not wildly off) get you a higher temperature, perhaps even 1825 deg.

 

One thing I do with my ovens is give them full power and log the temperature every minute until it is at the highest temperature I will ever want. That way, I have a reference chart for setting achievable ramps.