Fluke true RMS meter - Page 1
Forum section: electronics / beginners

author: melvinkoshy
author_rank: Newbie
timestamp: October 29, 2022, 10:56:24 am
content: When I use Fluke multimeter clampmeter [true RMS meter] to measure AC current in a 3.5C XLPE cable, does it give the value of leakage current or RMS value of current per phase through the cable?

author: rsjsouza
author_rank: Super Contributor
timestamp: October 29, 2022, 11:07:19 am
content: An image or diagram of what you are doing and the type of meter you are using will help get to the core of the question.If you are talking about a standard multimeter and not an insulation multimeter (Fluke 1507, 1577, 1578, for example), then the current measured of a given phase will be its RMS value. If you measure the GND/Earth wire, it will measure the RMS value of the leakage current (if any) to the protective earth ground.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 29, 2022, 01:22:11 pm
content: A clamp meter will measure the sum of all current running through it. So with a multi wire cable powering something the current flowing to the load and back will cancel out. The clamp meter would only masure the current flow back on a different way, a bit like a GFI only reacting to leakage current.So to measure the load current one needs to seprate the wires and measure only 1 wire at a time.

author: elekorsi
author_rank: Regular Contributor
timestamp: October 30, 2022, 05:30:16 pm
content: As @Kleinstein said, to measure current per conductor you clamp only that one conductor.To measure leakeage current, you clamp Phases and neutral conductors (L1+L2+L3+N) together. Problem is that regular clamp meters usually don't have the required resolution for leakage current measurments, which usually are in mA ranges.

author: EPAIII
author_rank: Super Contributor
timestamp: October 31, 2022, 09:41:12 am
content: A Flute or any other clamp-on meter will measure the algebraic sum total of the currents in ALL the conductors that pass through it.XLPE is not a type of cable. It is a type of insulation (cross linked polyethylene) and it can be used in many types of cables which can have one or many conductors and may be shielded or not. They may even have multiple shields.You mention leakage current. A clamp-on meter that is used on a two conductor lamp cord can give you a measure of leakage current because the leakage current is equal to that algebraic sum of the two currents flowing in it: the current to the lamp and the current flowing back from the lamp. These two currents are normally in opposite directions and, with no leakage at the lamp, the difference will be zero: they will completely cancel. If there is any leakage then they will not cancel completely and the clamp-on meter will show that difference, which then would be the leakage current. Remember, there are "if"s in that.But, since you do not specify just what type of cable this is, it is impossible to say if the current measured is from just one conductor or from many. It could have circuits with actual earth return paths, in which the meter would show the full current for those circuits (because the earth itself is not inside the clamp). Or there could be several/many different circuits, each with different characteristics.In order to answer your question we need to know more about your cable. Perhaps a lot more. Pictures are always nice; a picture of the CABLE, that is. We all know what clamp-on meters look like (or at least we should).