Happy New Year!

I have ordered some large equipment from China. One component is a tube for heating air going into a tank. It is supposed to go up to 200 deg c, but only goes up to about 26 deg. i have gone back and forth with the manufacturer for a long time now with no sulution. i decided to take a look at the wiring for it and appears it was wired wrong, but i'm not really sure how they should all be connected.

I have 200v 3-phase 3-wire source. There are 3 elements with the 6 posts coming out the end of the tube and a fan at the other end. i have created a diagram that shows the posts in their current configuration. Each element is its own color, ie the two red circles indicate where the two posts for that certain element comes out the top.

thank you for your help!
FYI I have removed each element and tested it with single phase power to make sure that it does indeed heat up. Those tests were ok.

 

You can wire them two ways,
1) in Delta formation
2) in Star formation

Delta will give you the hottest temperature, what is the resistance of the elements and what is the wattage it's supposed to be?

 

Thank you for your help!

That's my problem. I have no information on them and getting any useful information from the manufacturers is near impossible. I think they are as fed up with my constant questions as i am asking them. LOL. My requirements were to get it to 200 deg c, they put together the system. the fan blows at 15 cubic meters per minute, they told me later that it needed a 15kw line, even though the relay in the control panel is only raterd to 38 amps. the way it was wired before only drew 2.4 amps even when setup with a 100 amp line, so i'm fairly certain it wasn't set up right. the relay turns on and off as needed, but since it has never reached temp, it just stays in the on position.

the elements are similar to what is found on this page....
https://www.backerfacsa.es/air-heating-elements-for-industrial-applications-p-1-en


they are 77-85 cm long. can the resistance be calculated? are there standards for them?

 

Okay sounds like it was wired in Star formation, you need to wire them by linking the terminals shown.

You need a multimeter to check the resistance of the elements.

 

Looking at the diagrams here
https://www.reheatek.com/news/wiring-methods-of-heating-elements.html
i can safely say that i think it was wired or supposed to be wired, in star.

For testing for ohms, I will need to head out there tomorrow (it's 9:40 pm right now here).

Thanks for your help!!!

 

sorry when i posted that last reply, the pics you uploaded weren't showing yet. Now i see them. thank you so much!!

 

Hello again. I tested the resistance in the heating elements and each one is about 20 ohms. i am trying to get information from the manufacturer as to whether they are made for 200v or 380v. i have read that 3 phase in china is 380v.

 

Hello again. I tested the resistance in the heating elements and each one is about 20 ohms. i am trying to get information from the manufacturer as to whether they are made for 200v or 380v. i have read that 3 phase in china is 380v.

Are you referring Phase Voltage (200 V) or Phase - Phase Voltage ( 380)
You can safely connect the heater in Star Mode and not blow off anything, but not in Delta unless you are absolutely sure.

 

Well now i'm nervous again. LOL. Haven't connected them yet because my electrician was out until the 3rd for NY. We were troubleshooting the problem before the break and that left the line to the machine disconnnected for now. I'll test between the phases and write back here. I don't think there is a 4th wire for the 3 phase system. If it is wired in star, does it not need the neutral?
I will post back once I find the phase to phase voltage at the box.

 

No, the star does not require a Neutral, the 4th wire.

 

each phase tests 200v. no neutral line. so in delta would these run at 346 or 200?

 

there is a possiblity it was grounding to the chassis. two of the 12 ceramic insulators were broken and/or missing. i've fixed up a workaround to prevent them from touching the chassis until i can get replacements. i can't seem to find just the insulators here in Japan, so it will take a while. i plan to have my electrician here tomorrow. the main power line to our equipment is not connected atm.

 

Star connection does not need a neutral, but some codes require that neutral be brought to the application in case the installation changes.
But iif you decide to run only one or two of the heaters then you will need the neutral wire.

 

Hello again. I finally go the electrician out a few days ago to test things with a stronger line. in the meantime, i added an SCR voltage regulator to the fan so i could slow it down a bit. after fixing the problem with the insulators and the elements grounding to the chassis, I was able to get it up to 49 deg c, which is still not high enough. interestingly, the power was only 2.4 amps per line before and after the above.

I am finally getting some help from the manufacturer and they are offering to send me knew heating elements. they are offering a 15kw heater. I'm fairly sure this means three 5kw heaters. I am not sure what the current elements are rated at. i asked several times, but they've ignored that question every time.

so my next problem is this. 15kw means 75 amps total with 200v. the control panel has 3p relay rated for 38 amps. is this 38 amps for each line or for the whole circuit? if it is for each line, it sounds like it would be fine and not need to be swapped out with a more powerful one.

thanks in advance for your help. i'm excited to finally see this thing working correctly in the future.

 

they finally got back to me. the current ones are 11kw/380-400v. so i think they are safe to wire up in delta. i may get them to go ahead and send 15kw heaters as a backup. as long as the relay and source line is strong enough, this seems like it'll work. and a 400v heater will only run at 25% at 200v, right? by that calculation, i'm guessing it'll run somewhere between 3-4 times hotter than before...

 

Very interesting. And certainly a 400 volt 11kW heater will only run at 25% power at half voltage. The benefit being that it should last a long time.
It would certainly be useful to deal with a supplier that provided correct information about the products they sell.