IET logo
 
IET
Decrease font size
Increase font size
Topic Title: Anyone seen these before?
Topic Summary:
Created On: 10 July 2014 06:45 AM
Status: Post and Reply
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 10 July 2014 06:45 AM
User is online View Users Profile Print this message


Avatar for leckie.
leckie

Posts: 1864
Joined: 21 November 2008

A bit of kit to check for stray voltages when testing.

https://www.test4less.co.uk/details.asp?ProductID=1701

I was wondering if it might be useful, anyone got one or tried one?
 10 July 2014 07:15 AM
User is online View Users Profile Print this message


Avatar for GeoffBlackwell.
GeoffBlackwell

Posts: 3526
Joined: 18 January 2003

My Fluke multimeter has that facility built in - very useful as it flattens any stray induced voltages. It basically 'dumb's down' the meter by reducing its input impedance.

This makes it bit more like an old AVO .

Regards

Geoff Blackwell
 10 July 2014 09:48 AM
User is offline View Users Profile Print this message


Avatar for davezawadi.
davezawadi

Posts: 2656
Joined: 26 June 2002

Messy looking bit of SWA there Geoff, did you find it on the forum?
AVOs are good for reliable readings when the going gets difficult, but mine hasn't seen electricity for a long time, bit of a museum piece now

-------------------------
David
CEng etc, don't ask, its a result not a question!
 10 July 2014 11:29 AM
User is online View Users Profile Print this message


Avatar for GeoffBlackwell.
GeoffBlackwell

Posts: 3526
Joined: 18 January 2003

Originally posted by: davezawadi
Messy looking bit of SWA there Geoff, did you find it on the forum?


I took that picture in an installation I inspected. It demonstrates the folly of relying on continuity test data as a sole means of assess the Strength & Capability (Reg 8 EWR) of an earthing system - however, I am sure none of our readers do that - do they? .

Regards

Geoff Blackwell
 10 July 2014 01:00 PM
User is offline View Users Profile Print this message


Avatar for slittle.
slittle

Posts: 3510
Joined: 22 November 2007

My AVO has become a bit like yours I suspect David, It lives in the corner of the office collecting dust.

My weapon of choice these days being a fluke dmm. That said I still keep an analogue multimeter in there for those times when you need to watch a needle rather than digits to see things.


Stu
 10 July 2014 01:27 PM
User is offline View Users Profile Print this message


Avatar for mapj1.
mapj1

Posts: 2795
Joined: 22 July 2004

The nice thing about the analogue machines is they are largely impervious to RF and fast transient stuff, and you can measure volts and amps without batteries, so leave it permanently in circuit.
I've not used one of the things in the OP, but I carry some resistors and capacitors on clipleads that end in stacking bananas that are very useful for trying the effect of a light lunch
edit light load stackable test plug/sockets that are a considerable sight cheaper than that offering, and allow a greater variety of experiments.

In the absence of a proper datasheet, which is sloppy of them, I would imagine it contains nothing more than an RC filter, but values can only guess.

I'm sure if I was a fussier fellow I could make something that met the GS38 requirements as well.

In terms of pulling down on cable capacitances of perhaps a nanofarad or two, then 100nF & a few tens of K is enough. Some thought is needed in terms of voltage ratings of components used this way, just in case they end up across 415VAC for a bit.

-------------------------
regards Mike
 10 July 2014 02:17 PM
User is online View Users Profile Print this message


Avatar for leckie.
leckie

Posts: 1864
Joined: 21 November 2008

I think I read it was basically a 3Kohm resistor across the terminal. this would make a high resistance meter a "lower" resistance meter and provide somewhere for the stray voltages to go.

As you say, probably easy to knock one up but not sure how compliant with GS88 it would be.
 10 July 2014 02:32 PM
User is offline View Users Profile Print this message


Avatar for mapj1.
mapj1

Posts: 2795
Joined: 22 July 2004

ooh. If that's true, then 3K across the mains for more then a few seconds will sweat a bit !!
(17 watts on 240V to be precise - same heat as a small soldering iron, and more like 60watts on phase to phase) I'd prefer something more in the range 20-50K myself.

towards the bottom of the page
http://www.rapidonline.com/ele...s-series-517872

a couple heat sunk to a metal plate in a box.
or http://www.rapidonline.com/ele...tor-62-8272#techSpecs
in series on ceramic choc blocs.

-------------------------
regards Mike

Edited: 10 July 2014 at 02:43 PM by mapj1
 10 July 2014 03:32 PM
User is online View Users Profile Print this message


Avatar for leckie.
leckie

Posts: 1864
Joined: 21 November 2008

 10 July 2014 04:31 PM
User is offline View Users Profile Print this message


Avatar for mapj1.
mapj1

Posts: 2795
Joined: 22 July 2004

Well I agree they say
Specifications
Voltages up to 1000 volts continuous can be safely applied to
the Adapter without damage.
Operation Temperature
-20 °C to +55 °C (-40 °F to 131 °F)
Altitude
2,000 Meters Operating
Humidity
90 % at 0 to 35 °C (32 °F to 95 °F), 70 % at 35 to 55 °C
(95 °F to 131 °F)
Nominal Resistance
3,000 ? @ 25 °C (77 °F)
Instrument Compatibility


However in reality the two statements in bold are not compatible, if the resistor is simply across the terminals.
I have just dropped their chaps an Email - let's see if I get anything.

edited to change will drop to have dropped.

-------------------------
regards Mike

Edited: 10 July 2014 at 04:44 PM by mapj1
Statistics

See Also:



FuseTalk Standard Edition v3.2 - © 1999-2014 FuseTalk Inc. All rights reserved.