What kind of protection shoul I use in zone 1?

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

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

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

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 [B]hazardous area[/B] if you put zener barrier in Pressurized enclosure or Flameproof Enclosure.
Remember Zener barrier and Galvanic barrier are classified as ASSOCIATED APPARATUS.

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

[QUOTE=joaopedro;165766].....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??......[/QUOTE]

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.

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