Cable gland size higher than the cable size. 1

[eletest]

For our newly installed induction motor , the cable size used is 3C x 95 sq mm ( PVC , Armoured) , whereas the gland (double compression) size is higher ( suitable for 3C x 120 sq mm) . As a result there is a slight gap between the cable and the gland. Does this effect the Ex d protection of the motor.I don't have the option of replacing the gland immediately. What are the options available for operating the motor.

 

[ScottyUK]

Glands usually have a stated range of cable sizes for which they are suited. If you go outside of this range then normally the haz area certification is void. That would leave your options as:
[ul]
[li]don't run the motor[/li]
[li]run the motor, hope for the best, and get away with it[/li]
[li]run the motor, hope for the best, and blow something up.[/li]
[/ul]

Why can't you get a gland? It is a common size.

 

[Compositepro]

A alternative to ex-proof design is to use purged enclosures with positive pressure safety switch to cut-off power in case of loss of purge air. So you could purge the motor with a compressed air supply, but it is probably easier and faster to get the correct gland seal.

 

[ScottyUK]

If the motor is plated as an Ex 'd' type then applying Ex 'p' techniques to it will not result in a certified system.

You might as well fill the terminal box with sand and claim Ex 'q' or with compound and claim Ex 'm' protection: these would be equally invalid from a certification point of view, but at least they would save drilling holes in the motor casing and ruining it for use as an Ex 'd' type when the correct gland arrives.

 

[racookpe1978]

Hmmmn.

QA me here - please! - but if the wire size is provided from the motor manufacturer (and thereby assumed to be large enough diameter NOT to be overheating under the current needed by the motor, AND the gland is a specified size to obtain waterproofing and sealing, could he not wrap the cable coil with tape/sealant and get the needed closure against vapor and gas and dirt?

 

[ScottyUK]

From a compliance point of view, not a chance.

Ex 'd' equipment is the European equivalent of explosion-proof equipment in North America. A carefully controlled flamepath allows explosion by-products to vent but reduces the temperature of the gases to a non-incendive level. I doubt you could get a sufficiently robust seal to withstand an internal explosion using tape. You could probably make it waterproof if you asked it nicely not to blow up. ;-)

 

[7anoter4]

In my opinion, you have to use 3*120 sqr.mm cable entering the gland-if this is the rated size of the gland. If the cable is too long you may use a junction box- in a non-hazardous atmosphere -and connect the 3*95 with 3*120 sqr.mm. [Or to use a hazardous location rated junction box].