Potting Compound

Patton & Cooke Co. recommends the use of an approved “potting compound” to fill the back body of the coupler. By filling the rear body of the coupler with a re-enterable potting compound, the air at the base of the insulators is displaced by compound, so partial discharge is minimized, if not eliminated entirely. At the very minimum we recommend that each of the phase insulator tubes be filled with compound.

For applications in areas of extreme heat and humidity or in areas where the day to night ambient temperatures vary widely, it is common to have condensation form on the interior of the couplers. The only way to eliminate this condensation problem is to fill the back body with potting compound.

Patton & Cooke 5 and 8 couplers require one (1) 3000 gram kit to fill. 15kV couplers require two (2) 3000 gram kits to fill. They do not fill the coupler completely, but about 70% or 80%. It is important that the backs of the insulators are filled and do not have any air pockets. The best way to do this is by having the coupler pointing downward (see illustration below)

From this picture you can see that the compound should fill the back of the insulators - but leave airspace at the top (the airspace is important to allow for expansion of the compound). You should never fill the coupler when it is lying parallel with the ground because there is a possibility for leaving an air pocket near the insulators. Using an angle such as I have drawn is ideal. It will take about an hour for the compound to set up but doing it this way will ensure the best result.

There are 2 ways you can put the compound in:

1. You can use the filler plug on the side of the body. Or,

2. if this is being done at the same time as the termination, then you can pour the compound through the back of the coupler before putting the entrance fitting kit on. This has the advantage of providing a larger entry point for the compound than the filler cap.*

*Please be advised that if you do this you must complete the installation of the entrance fitting so that the cable is securely fixed in the center of the coupler (otherwise any movement during the subsequent installation will damage the compound – like sticking a fork in jello).