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Application of anti-condensation heater for a 6.6kV Junction Box

Application of anti-condensation heater for a 6.6kV Junction Box

Application of anti-condensation heater for a 6.6kV Junction Box

I have to procure some outdoor power Junction Boxes (JB) to be used in the offshore oil producing platforms. The purpose is to provide a junction point between the subsea composite cable and the above sea 6.6kV and Fiber Optic (FO) cables. The location of installation is classified as hazardous area.

This installation will be in the Middle Eastern region, where the ambient temperature goes above 50 deg C in the summer with close to 100% humidity.

I am specifying the junction box suitable for the hazardous area Ex 'e' type and IP56 enclosure. Also I have specified the requirement of breather. The volume of the box is about 0.4525 cubic meter. Now, my query is that whether I need to specify space heater (anti-condensation heater) for the junction box?

Also I would appreciate if someone enlightens me on what is the criteria to specify the space heater.

Any industry standard available for reference on this subject?

Also a question regarding the breather:
Will the breather prevent the moisture entry? or it will only restrict the free air movement.

RE: Application of anti-condensation heater for a 6.6kV Junction Box


I have recently designed an enclosure for installation on an offshore oil rig. The customer had a very, very detailed design guide. Perhaps your customer has one too. Trial and error is the wrong way to learn safety.

You can buy breather desiccators. I have used these on otherwise sealed airborne systems.

You need a heater at 50°C?


RE: Application of anti-condensation heater for a 6.6kV Junction Box

Condensation is often caused by the thermal lag of enclosed components.
When the RH is high, a rise in ambient temperature may leave the temperature of internal components below the dew point.
This will cause instant condensation, even at high temperatures.
The core iron of halted motors and generators is particularly susceptible, even at elevated temperatures

"Why not the best?"
Jimmy Carter

RE: Application of anti-condensation heater for a 6.6kV Junction Box

The simplest and most reliable setup IMHO is a mass of desiccant. But that requires periodic recharging that may be unacceptable per your maintenance plan. Another solution, though less reliable, is a plain old wound resistor you can generate heat with by running current through it. The current would have to be controlled with a controller CCA with an onboard humidity sensor and dry bulb temperature sensor so you can calculate the dew point temperature and control the internal temperature accordingly. Of course if it's feasible, you could just keep heating the box all the time. That way you would not need the sensor CCA. A fan may be needed to mix the air but I supposed it depends on how well sealed the box is.

ElectroMechanical Product Development
(aka Electronic Packaging)
UMD 1984
UCF 1993

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