Taping Medium Voltage Cable Terminations

[RedBrick]

We tested some bar type current transformers in a piece of MV switchgear recently that required us to remove the tape from the 15kV cable terminations. What is the reason for taping these terminations and what can happen if they aren't taped? There were also some terminations in this piece of gear that weren't taped and there didn't seem to be any signs of damage.

The piece of switchgear we were working on was an Eaton VacClad-W. The manual for this equipment list "Metal-clad switchgear field taping procedure" in the contents. Goes on to say:

- "For incoming or outgoing terminations, these approved materials and not supplied by Eaton and must be
obtained and installed by others as identified in the definitions."

- "Failure to install field insulation where necessary in accordance with these instructions will compromise the
electrical ratings of the switchgear assembly. Install field insulation to maintain the electrical ratings."


Powell Article:
https://www.powellind.com/sites/down...onnections.pdf

Anyone have experience with this kind of termination?

[Kalbi_Rob]

We tested some bar type current transformers in a piece of MV switchgear recently that required us to remove the tape from the 15kV cable terminations. What is the reason for taping these terminations and what can happen if they aren't taped? There were also some terminations in this piece of gear that weren't taped and there didn't seem to be any signs of damage.

The piece of switchgear we were working on was an Eaton VacClad-W. The manual for this equipment list "Metal-clad switchgear field taping procedure" in the contents. Goes on to say:

- "For incoming or outgoing terminations, these approved materials and not supplied by Eaton and must be
obtained and installed by others as identified in the definitions."

- "Failure to install field insulation where necessary in accordance with these instructions will compromise the
electrical ratings of the switchgear assembly. Install field insulation to maintain the electrical ratings."


Powell Article:
https://www.powellind.com/sites/down...onnections.pdf

Anyone have experience with this kind of termination?

Typically, if the terminations fall within the acceptable clearance requirements for the rated voltage class, rubber and vinyl tape is used to assist in insulating the terminations. This reduces the corona discharge capabilities to jump to ground or other phases. Otherwise it is extra preventative measures taken by electricians.

[RedBrick]

I was able to reach out to Powell and find some additional information. See article below. They pointed me to IEEE C37.20.2 (Standard For Metal-Clad Switchgear)

Two Points From That Standard:

1. 3.1.5 Metal-Clad Switchgear Characteristics
(e) Primary bus conductors and connections are covered with insulating
material throughout.

2. 7.9 Insulating Materials For Covering Buses & Connections
"The insulating covering is a requirement of metal-clad switchgear and
is provided to minimize the possibility of communicating faults and
prevent the development of bus faults that would result if foreign
objects momentarily contacted bare bus"

Seems as though it is required to meet the standard definition of Metal-Clad Switchgear at the least, along with any other reason.


Powell Insulation of Bus Joints:
https://www.powellind.com/sites/down...s%20Joints.pdf

[RedBrick]

3M MEDIUM VOLTAGE TAPE METHODS.pdf

Here is a 3M document on their recommended taping procedure for this scenario.