Help with compatability

[Reylocs]

Hello all, this is my first post.

I am putting together a glass furnace. I bought some parts from someone on internet.( a Chromalox 2104 temp controller and a Watlow 80 amp SCR) When I purchased these, i told the guy "i knew nothing about electronics" " will these work for what I want to do". He said yes, and said he hooked them up and tested them before he sent them out. since the guy has instructed others in furnace builds i trusted him. So.
I hooked them both up and nothing is happening. So i was looking in the manuals and something seems strange to me.( I need to say that I have very very limited knowledge of electronics) so please bare with my limitations.

The input specs for the watlow SCR are - a 4 to 20ma (dc) loop powered. Type F0 and type F1 options only. (Requires current source with 6.2 volts peak) I have the F0 model.

My output on my Chromalox 2104 temp controller is 4 to 20ma at 24 volts, if i am reading it correctly. These two devices are not compatable, correct?
Am i reading this correctly?

Thanks for helping

 

[AnalogKid]

Not necessarily. There is a difference between the maximum voltage headroom of a 4-20 mA output and the minimum voltage drop of a 4-20 mA input. Please post the datasheets (or links).

ak

 

[Alec_t]

Welcome to EP!

My output on my Chromalox 2104 temp controller is 4 to 20ma at 24 volts, if i am reading it correctly.

That depends on the particular model and its jumper settings, from my understanding of the spec. What is the full product code? Which terminals are you using for output?
If you're actually getting 4-20mA out, then that should be fine for the Watlow, which only 'soaks up' 6.2V of the 24V which the 2104 provides.

 

[Reylocs]

The model of the temp controller is Chromalox 2104 it an (2104-AR-100) the Watlow SCR is DD10-24F0-0000;. Im sorry i dont know how to upload the file.

 

[Reylocs]

I am using terminal 10 and 11 on the temp control and 3 and 4 on the SCR. 10 and 3 being the positive and 11 and 4 being negative. Also here are some pics. of the SCR manual.

 

[Reylocs]

The chromalox 2104. Is technical manual -0037-75276. I couldnt post the link.

 

[Reylocs]

I have the heating elements all set up in my garage. I have spoken to a guy at Chromalox briefly, on my temp control, there is a light that comes on that tells you when the controller is applying signal to the SCR. That light is coming on. The guy i spoke to said if that light is coming on, then there should be a signal. I do have a good meter that measures ma, but I dont know how to test for ma.

I did look online how to make a ma test but im not sure so havent done that yet.

 

[Alec_t]

The safest way to test the controller would be to connect a 1kΩ resistor between terminals 10 and 11 of the controller, set the meter on a range to measure VOLTS (over 20V), and measure the voltage between those terminals. You should get readings between 4V and 20V, depending what your temperature settings are.

 

[Reylocs]

How "rugged" is a 4 to 20ma output. I have done nothing that could have "injured" the output that I know of. I made all connections with power off (controller unplugged) the connections are super simple, + and -, the terminals were never in question. I just have no idea why there is nothing happening. Chromalox says if the output light is on then the contacts are closing therefore a signal should be present.

I will grab a 1000 ohm resistor and check voltage.

 

[Reylocs]

Is anyone familiar with this controller (2104)? That might help me configure.

 

[Reylocs]

Does the wattage of resistor matter. The manual says 4 to 20ma into a 0-800 ohm controller. Will 1000 ohm 1/4 watt work?

 

[Alec_t]

The 1k would dissipate about 1/2 Watt.

 

[Reylocs]

My controller is puting out nothing. I have done nothing but hook these two devices together. The seller said they were tested together before he shipped them and they worked. I get them hook them up properly and nothing. I guess its my fault for not buying new.

 

[Alec_t]

I've just had another look at the datasheet. You say that the model is a 2104-AR-100.
From the attached section of the datasheet, if I'm reading it correctly, the 'AR-100' designates the output features as Analog/relay, dual relay, NO analog option, 12-24V supply. So presumably there is no 4-20mA current loop .

 

[Reylocs]

Yes, i just figured that out with the seller, he is sending the correct board.

Could you look at and comment on the SCR spec in the LINEARITY section, stating that it should have a maximum of 6.2 volts peak. At 19.5 to 19.9ma. Here is the picture from the manual. I believe the output of my ma signal is 24 volts. Im still confused about their compatability.

 

[Alec_t]

See post #3 .

 

[Reylocs]

Thank you, I seem to have another issue. After being told by the seller and looking at manual myself, i was told that terminals 10 and 11 were the correct terminals. I then, after looking at manual saw that terminal 10 and 2 are the 4-20ma output for the AR model which is a Analog/relay(AR) controller. I then measured 19 volts (across a 1k resistor) when the controller was putting a signal. out. Can someone confirm that 10 and 2 are the terminals i should be using. (This is shown in fig. 2:27 in cromalox manual) after talking with seller last night and deciding he sold me wrong configured controller, this morning i get an email stating i have a controller that works with the scr and terminals 10 and 2 are the correct terminals. Can someone confirm this.

Thanks for everyones help

 

[Alec_t]

Certainly Fig 2:27 indicates the terminals for output #1 as 10 and 2 for the AR model. Not the clearest of manuals, given the table I attached in post #14 . Your measurement confirms that the controller is actually driving 19mA via terminals 10 and 2 (assuming your '1k' is accurately 1k). What you'd expect with no temperature sensor attached. Hurrah! Looks like you're good to go.