Pilot Lights in Intrinsically Safe circuts

[James Mcquade]

I saw the Class 1 rating, but it does not designate Div1, Div2.
Also, what is the A196 in front of the Class 1?
i would definitely investigate that.
The issue i ran into with my last design was that the devices had to say C1,D1/D2. Right now the big issue is that your customer did not approve the device. if you cannot get him to accept the device, you must plan for an alternative. i am all out of ideas.
regards,
james

 

[mobil1syn]

so i was able to get on the phone with the customer, he has no issue with the design and agrees that it is a simple device. the push back he getting from his internal team is that its not on the label (que tommy boy, the guarantee needs to be on the box) IS, then it cant be used. which is not true.

so the next question becomes ... is a rectifier considered a simple device and/or does it store energy?

"These devices contain a bridge rectifier which allows you to apply both AC and DC voltages to them. Even though the terminals are labeled X1 (+) and X2 (-), the bridge rectifier circuit will protect the device if the (-) is applied to X1 and the (+) is applied to X2 when DC control voltages are being used."

 

[James Mcquade]

the device is listed as 24 volts dc and 8.5 ma.
you need to look up the intrensic barrier output data and also look up the intrensic safety section of nec 70.
in my opinion, 24 volts and 8.5 ma violates the intrensic rule.
if the cover and bulb gets broke, there is enough energy with a spark to ignite the gas. again, this is my opinion.
maybe jaref will add to the post.
james

 

[mobil1syn]

Simple Apparatus [as applied to Hazardous (Classified) Locations]. An electrical component or combination of components of simple construction with well-defined electrical parameters that does not generate more than 1.5 volts, 100 mA, and 25 mW, or a passive component that does not dissipate more than 1.3 watts and is compatible with the intrinsic safety of the circuit in which it is used. (CMP-14)

Informational Note: The following apparatus are examples of simple apparatus:
(1) Passive components; for example, switches, junction boxes, resistance temperature devices, and simple semiconductor devices such as LEDs
(2) Sources of stored energy consisting of single components in simple circuits with well-defined parameters; for example, capacitors or inductors, whose values are considered
when determining the overall safety of the system
(3) Sources of generated energy; for example, thermocouples and photocells, that do not generate more than 1.5 volts, 100 mA, and 25 mW

*IF* it classifies as a simple apparatus (since a bridge rectifier is simply an array of diodes) it is well below the 1.3W classification so there should be no issue. NOW if it is not a simple apparatus I am screwed.

 

[James Mcquade]

in your definition of Simple apparatus.
1. 24 volts at 8.5 ma is .204 watts or 204 milliwatts, which is more than the 25mw allowed.
2. a passive component must not dissipate more than 1.3 watts AND is compatible with the intrensic safety of the circuit in which it is used.
IF you are using the led in an intrensic safey circuit(safey barrier), i see no problem, but i interpet your post as using the led on a circuit by itself with no safety barrier. if this is true, then you are not using a safety circuit and i would not allow the device to be used.
james

 

[mobil1syn]

there is a barrier in the plant control panel, the simple device approach is because the device isnt "IS" rated on the label like the SOVs or Instruments on the package

https://files.pepperl-fuchs.com/webcat/navi/productInfo/pds/243734_eng.pdf

 

[mobil1syn]

just to close the loop on this for someone searching in the future ... in short since the -N374 powers the universal 3V LED it has a stepdown transformer in it. so you have to use the legacy full voltage contact block with a 24v LED.

https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/1127397

"the 800TC-N374 is NOT a simple device, thus is not suitable for an Intrinsically safe environment. As your customer mention, it does use circuitry that stores energy. So even though it is an LED light module, the circuitry inside keeps it from being considered a simple device.

With that said, Allen Bradley offers the 800T-N330 full voltage module. This is the predecessor to the 800TC-N374, and is considered a simple device, as noted in the attached knowledge base article. This unit simply passes voltage through to the bulb, so the LED Bulb has to be matched to the voltage the end user will be using. The 800TC-N374 transforms the voltage down to 3V to fit a special LED, and this process is what keeps it from being IS rated.”

 

[James Mcquade]

the 800t series is rated nema 12,13, 4 and i do not believe it is rated for class 1 or class 2 environments. if the environment is rated class 1 or class 2, and it does not meet the rating requirements, they cannot be used.
james