Concrete is a lousy insulator. It is frequently used as a "poor" conductor in grounding systems. I think the conductivity of concrete was first described by Uffer (spelling ???) after his work on protective grounding of munitions bunkers. I can't find my copy of his paper right now so I can't quote numbers. But, with cement being so hydroscopic the conductivity will have a wide range. I have actually measured it in the (10s)Ohm / meter-sq. range in one instance Castable ceramics are much better. Used them in a prior life -- they worked well. Regards, Michael Taylor.
-----Original Message----- From: POWELL, DOUG [mailto:[email protected]] Sent: Friday, August 20, 1999 3:40 PM To: EMC-PSTC (E-mail) Subject: Concrete as an insulator??? Hello all, I have a very innovative engineer who has come up with a design idea that uses concrete as an insulating compound in a very large inductor for a 200 kW switching power supply. Yup, this is the stuff you buy down at the local building supply company. He was very proud of the idea, but until he came up with it I think he was pretty desperate. I'm thinking I should make him desperate again but would like to be able to give him a clearly reasoned-out explanation. Has anyone ever had experience with using concrete or mortar in a high voltage application? What are the concerns here? It is my understanding that it does not actually "dry" but it cures with all the water contained inside. thanks, -doug ======================================= Douglas E. Powell, Compliance Engineer Advanced Energy Industries, Inc. 1625 Sharp Point Dr. Fort Collins, Colorado 80525 USA --------------------------------------- 970-407-6410 (phone) 970-407-5410 (e-fax) mailto:[email protected] <mailto:[email protected]> http://www.advanced-energy.com <http://www.advanced-energy.com/> ======================================= --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators). --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
