At 06:07 AM 8/26/2004, Lawrence Lile wrote: >Say I connect these CT's up successfully, and I can measure current >through the shield (I am still not sure of this). The CT wires are rated >600 volts. Are people going to get zapped by these wires as they exit the >metal clad switchgear? I am thinking corona discharge... I'd ensure that one lead from each CT is grounded at all times. That stops them from capacitively coupling to large electric fields. This would normally be at the data logger but you need to ensure they are grounded while the data logger is disconnected. I'm glad that you mentioned that the CTs are voltage output 'cuz I'd otherwise be cautioning you about not allowing them to go open circuit at any time. My trick is to connect a small bridge rectifier across the CT leads with the output of the bridge shorted. Burden voltage as seen at the output of the CT is usually well under 0.5V - way below the knee of two series diodes. If I'm concerned that the burden voltage might be a bit higher, I replace the short at the output of the bridge rectifier with a single forward-connected diode - raises the clamp voltage to 3 diode drops. As far as measuring the 4160V is concerned, you need proper Potential Transformers. Your power company should have these available for their own use - perhaps you could arrange to borrow theirs. I'd put a plug in here about the PT and CT boxes that we sell but they don't operate at those voltages (intended for Field winding voltage and current measurements in large generators). dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 20 years of Engineering Innovation (1984 - 2004) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body