[Dsg-halla_ecal] emergency shutdown for ECal

Tue Jul 11 18:01:04 EDT 2023

While I’d prefer something passive as well thus far we haven’t been able to find something suitable.

Interestingly enough the Omega being used in the current system isn’t passive at all.

So while not passive it is independent, if that is okay we could sort of duplicate that by having each power supply output go through a NO relay that an Omega would control. This does mean it would be an all or nothing system as far as interlocks are concerned, i.e. one temperature probe would trip off all the supplies. Finding relays that handle the current should not be difficult or expensive.

On Jul 11, 2023, at 5:38 PM, Donald Jones <jonesdc at jlab.org> wrote:

Right. I told Ed that a Klixon-like solution will be difficult because those instruments aren't intended to be placed inside a hot region. They just can't survive. He prefers something passive, but you might convince him that this is sufficient.
As far as shielding goes, I discussed it with Jack before he left and we decided it would likely be a good idea to have a little bunker to house the power supplies. It will have to sit on the floor not the platform and have sufficiently long cords to allow for the motion of the detector over the different kinematics. If we make the walls of the bunker thick enough, perhaps your cRIOs could survive in there as well. We will learn a lot from our beam test this Fall.
-Don

Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
________________________________
From: Marc Mcmullen <mcmullen at jlab.org>
Sent: Tuesday, July 11, 2023 5:31 PM
To: Donald Jones <jonesdc at jlab.org>; Brian Eng <beng at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: emergency shutdown for ECal

Brian and I have discussed using Klixons, as well as linear heat detection. The issue with both is the extreme temperatures proposed in the detector volume (much greater than mid 200C). You might want to reach out to some of those manufacturers to see if they make higher temperature models.

Also, it seems at some point you’re going to have to consider the location of the system components. Neither the cRIOs or power supples are rad hard, so shielding would be more than appropriate.

Marc

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________________________________
From: Donald Jones <jonesdc at jlab.org>
Sent: Tuesday, July 11, 2023 5:21:31 PM
To: Marc Mcmullen <mcmullen at jlab.org>; Brian Eng <beng at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: emergency shutdown for ECal

Thanks, Marc. Looks like some positive results. I remain somewhat worried about this solution because it does not utilize robust independent components. The shutoff relies on circuitry inside the power supply that interprets a voltage level and then turns the circuit on or off accordingly. I believe this isn't a radiation hard internal relay, but a complex circuit board which I suspect is susceptible to radiation damage. How certain we be that neutrons won't damage the circuitry so that the circuit is always stuck on or off? You could argue that will only happen at the individual power supply level and not the whole detector. Maybe at that point we would just swap out the individual power supply that failed.
Regardless, this will have to pass through Ed Folts and Rick Adrover. Ed expressed his desire for a completely passive system similar to a Klixon thermal switch that shuts everything down above a certain temperature. Perhaps they will be just fine with your solution. I will say that the current target oven in Hall A has an excess thermal shutdown implemented that passed safety muster. Ellen Becker is the owner and implementer of that system.

I have been developing the power supply system and we need to meet to make sure the interface between our systems works.
-Don

Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
________________________________
From: Marc Mcmullen <mcmullen at jlab.org>
Sent: Tuesday, July 11, 2023 4:47 PM
To: Brian Eng <beng at jlab.org>; Donald Jones <jonesdc at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: emergency shutdown for ECal

Hi Bogdan and Don,

We have done some testing using the supplies onboard 5VSB and the remote on/off circuit.

It looks like it should work for the over-temperature interlock. I will use the circuit to interlock the 6 supermodule teststand, the Omega process controller and the overall volume RTD (above the top two super module front flanges) will be used to trigger and latch the system.

In addition to testing this with the cRIO as the interlock trigger, we tested the circuit by physically removing the 5V from the test stand to ensure the system will disable the output of the supply due to failure of the any of the interlock components:

  *   If the power supply fails to supply the 5V...no output (system failure)
  *   If the interlocking relay fails to complete the circuit...no output (circuit failure)
  *   If the temperature goes out of range...no output (interlock engaged)

I am working on the major parts procurement list for the whole system  this week. Next week I will set a meeting to discuss the controls.

Regards,
Marc

________________________________
From: Brian Eng <beng at jlab.org>
Sent: Wednesday, July 5, 2023 9:27 AM
To: Marc Mcmullen <mcmullen at jlab.org>; Donald Jones <jonesdc at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: emergency shutdown for ECal

The +5V standby is always output (assuming the supply has AC input power) and can provide up to 0.5A of power. It is normally used to power things like secondary ICs that run on a lower voltage than the main supply provides.

The remote on/off functionality can either work with a switch (normal on/off [ relay closed/open]) OR a voltage. As you noted when using the switch style it's backwards from what we'd normally want, however for the voltage it is correct, i.e. it needs a voltage to power on and with no voltage applied it turns off.

Like Marc mentioned we're checking to see if we can combine these functions such that we don't need to provide an external voltage but rather use the standby voltage with an external relay to get switch like functionality. However, this requires testing and verification first.

________________________________
From: Dsg-halla_ecal <dsg-halla_ecal-bounces at jlab.org> on behalf of Donald Jones via Dsg-halla_ecal <dsg-halla_ecal at jlab.org>
Sent: Wednesday, July 5, 2023 8:50 AM
To: Marc Mcmullen <mcmullen at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: [Dsg-halla_ecal] emergency shutdown for ECal

Ok. My understanding is that there is a remote control input which operates like a switch with open=On and closed=Off which is opposite what we would normally think of, but which allows the unit to operate normally with this input completely disconnected and unused. There is also a 5Vsb input that puts the supply into standby mode when 5V at 0.5A is input. Multiply that by 43 zones and that's 21.5A of current on the input just to keep it in standby. Correct me if I misunderstand the documentation (attached). Furthermore, both of these control circuits (remote control and standby), go through black box processing/detection circuits. How much of a neutron dose before you lose that control and the heater is stuck on? We don't know, although we will have a better idea after our prototype in-beam test this Fall. Given that these controls are governed by unknown circuitry, I am recommending not using them for emergency controls. Ideally, we should have a standalone controller not linked in any way to our temperature control system and certainly not dependent on the LabVIEW GUI that simply shuts down the whole system if the temperature gets too high on any one of an array of thermocouples.
-Don

Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
________________________________
From: Marc Mcmullen <mcmullen at jlab.org>
Sent: Wednesday, July 5, 2023 8:31 AM
To: Donald Jones <jonesdc at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: emergency shutdown for ECal

Using an AC relay on the 120V is an option.

 However, The supply also has a 5V sense circuit that we are going to test. Essentially, removal of the 5V would disable output from the supply. But again, we have to test this with the controls before we can definitely say the best way. We will certainly rope in electrical safety on any plans.

I’ll look at my schedule and let you know when I’m available to meet.

Marc

________________________________
From: Donald Jones <jonesdc at jlab.org>
Sent: Wednesday, July 5, 2023 7:54:59 AM
To: Marc Mcmullen <mcmullen at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: emergency shutdown for ECal

Thanks, Marc. Is there a time you could meet me in Physics Storage at the test setup? I am reconfiguring things and want to make sure the RTDs end up in the correct places.
We should put the controls system on high priority. I was told that we have to have a complete electrical design approved by Electrical Safety before they will provide approval to even start building ECal which was supposed to be well underway by now. Also, I don't believe the remote shutoff is sufficiently robust to pass safety muster. It will work great for controls though. It's rather weird because the default state is on (switch open) and off (switch closed). Perhaps you could change the default using a relay whose default was closed? However, as a part of the safety shutdown system without an obvious physical switch being turned off, I don't think Electrical Safety will approve. Perhaps a set of relays similar to the ones you are currently using to switch power on and off at the AC mains level would be more appropriate. Anyway, I'll stop thinking out loud, but it might be a good idea to pull Rick Adrover in to this conversation to avoid wasting time on something he won't approve.
-Don

Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA
________________________________
From: Marc Mcmullen <mcmullen at jlab.org>
Sent: Wednesday, July 5, 2023 6:39 AM
To: Donald Jones <jonesdc at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: Re: emergency shutdown for ECal

Hi Don,

Brian and I are looking into the controls safety for the overall detector. Currently, on the 6 supermodule test stand we are using an Omega reading a single RTD at the top of the detector to remove power to the heaters.

The new LED drivers (adjustable power supplies) have a built-in remote shutoff. We are looking into using that circuit to remove output power from the supply.

I will set a meeting sometime this month and we can discuss the overall controls safety.

Marc
________________________________
From: Donald Jones <jonesdc at jlab.org>
Sent: Monday, July 3, 2023 3:58 PM
To: Marc Mcmullen <mcmullen at jlab.org>
Cc: dsg-halla_ecal at jlab.org <dsg-halla_ecal at jlab.org>
Subject: emergency shutdown for ECal

Hi Marc,
I am trying to think through how we (you) will be able to implement the over-temperature shutdown on the ECal heater system. I think you said that the LED driver supplies, replace the relays. My understanding was that you were planning to use an Omega process controller to shut off the relays in the event of an over-temp condition. Did I understand correctly and do we need to re-introduce them? Here is the layout of the electrical system as planned which has no emergency shutoff relay. We could in principle, connect the 120 VAC plugs into relays that are powered by the AC mains.
-Don
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-Don

Donald Jones
Hall A/C Staff Scientist
Jefferson Lab
Newport News, VA

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