What kind of protection shoul I use in zone 1?

[joaopedro]

hello,

What kind of proteccion should I use in an hazardous zone 1? I must use intrinsically safe circuit, with zener barriers and galvanis protection?

Thanks

JP

[ngovankhoi]

If you use Intrinsic Safety Ex for Zone 1, please use equipment be certified with:
Ia: Zone 0, 1, 2 allow 2 faults
Ib: Zone 1, 2 allow 1 faults


If you use Zener Barrier, please obey this principle:
Dedicated high-integrity earth: Required
Safety and Hazardous circuits area: connected
Field apparatus: 500V IR Test to Earth

If you use Galvanic Barrier, please obey this principle:
Safety and Hazardous circuits area: do not connect

[joaopedro]

Clarify me just a thing,

But if I have an zone 1, and use "ia"equipment ia (ex. pressure transmiter 4-20mA). I need to have a protection in my control panel that is placed in a non Hazardous area (ex. zener barrier or galvanic isolation"??

Thanks

JP

[ngovankhoi]

With your pressure transmiter ia 4-20mA in hazardous area, you use Zener barrier in non hazardous area.
But you also use zener barrier in hazardous area if you put zener barrier in Pressurized enclosure or Flameproof Enclosure.
Remember Zener barrier and Galvanic barrier are classified as ASSOCIATED APPARATUS.

[joaopedro]

More one thing, I have to use this protections in nonhazardous area? My question is: If I have the transmitter (Ex) in hazardous area (zone1), the signal come from the transmitter (4-20mA) can enter directly in my control panel without zener barrier or galvanic protections??

THanks for your help

JP

[spitfire6]

.....My question is: If I have the transmitter (Ex) in hazardous area (zone1), the signal come from the transmitter (4-20mA) can enter directly in my control panel without zener barrier or galvanic protections??......

You must connect your transmitter to a zener barrier or isolator located in control room. type [ex Ia] or [ex ib]. This is a requirement to prevent high voltages transferring to the transmitter in the hazardous area in the event of a fault in the controller or high currents in the event of a short circuit or ground fault at the transmitter.

I personally would chose galvanic isolation over a zener barrier as grounding is not so strict…
Do not connect signal ground at the transmitter.

Cheers,
Iain.

[ngovankhoi]

How do you send 4-20mA with Galvanic Barrier to Controller?