Alibaba Transaction Review: Taisuo CH902 Temperature Controller

I contacted Susan Taisuo via Alibaba.  They refuse to send free samples.  Here are the good points and bad points of ordering

1- Language barrier is there but seemed to mostly get past that

2- They only accept SWIFT wire transfers in payment – that means there is 35 US dollar charge on top of any order to pay for the transfer.  This is a real problem.  Technical things rarely go exactly right and with the language barrier its a real problem.  They suggest Western Union but that’s almost as expensive. Also Western Union is not popular in the USA.  Almost everyone has PayPal in the USA.  Suggested solution to this is GET A PAYPAL ACCOUNT! 

3- Two temperature controller parts did arrive quickly.

4- I ordered a temperature controller to control a refractory oven.  They made a mistake in what they told me and placed my most important out,  the SSR ( solid state relay ) driver in OUTPUT #2 location. Unfortunately this results in the output be suitable sign for controlling a refrigeration unit.  When the PROCESS VALUE > SET VALUE the output is turned on.  

When I contacted them with the problem they wanted me to pay shipping to get another set of samples with correct output sign.  Of course what I would be paying = SHIPPING + WIRE TRANSFER fee.  A bit annoying and does not indicate well for doing business with them. 

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I decided to do surgery on my and swap the output circuitry in the one they sent me.    Annoying but I am leaving the country soon for a while and do not want to take it along unless I need to.  Here are the results.      

 

Taisuo CH908 Temperature controller movie  ( controller on the right) – ( quicktime …I know…annoying….but the camera I had available only made *.mov )

 

1- Auto Tune does not seem to work.  When I click it on it keeps running up the temperature and never stops……..Thus I tuned this system by hand.

2- When the control loop appeared to reach equalibrium with SET VALUE = 140 the PROCESS VALUE = 131 !!! ??? — ( PV is supposed to adjust and control to the SV !!! )   I set the integral  and proportional term higher and higher.  No apparent difference in the feedback. 

3- Control window ( both heating and cooling ) where set to 1 second.  The output flickered very suspiciously.   View the E5AX controller movie to see how and at what rate the bulb should be flashing.

4- Temperature measured by the Taisuo CH908 unit is significantly different from a known good controller ( E5AX ).  The Taisuo unit read 130 degrees while the known good unit read 108 degrees.  I could tell from touch the bulb was much closer to 108 degrees than 130 degrees.   It was very comfortable to touch.  ( 130 would be painfully hot )

 

Summary: This controller appears not to be ready for use.  It has fatal flaws that prevent it from being used in any application.  I want to work with the people on it to use it in my product but they require an expensive wire transfer fee + shipping + ( time to run to bank to do this ).  Thus it appears I will not be able to use this unit in my products unless they change policies.

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What it is supposed to look like  

I set up an E5AX to work under the same conditions

E5AX temperature controller movie  – E5AX controller on the left is controlling the light bulb

Observations:

1- notice the green and red numbers are equal?  — ( on the E5AX controller on the left.  )  This is because the temperature controller controls the fraction of the time that the bulb is on to make it come to a temperature that matches the set temperature.

2- notice how the bulb does not flicker rapidly.  It turns on for the apropriate fraction of a 1 second window to arrive at a PV – ( bulb temperature)  exactly equal to the setting of the controller SV ( set value )

After seeing this you can realize that the Taisuo CH902 temperature controller needs alot of work.  It needs alot of help and will not work in ANY application as it presently stands.  It will be a waste of money and time in the present state of its design.