[RE-wrenches] To Megger or not to Megger

Tue Apr 28 07:59:20 PDT 2009

Matt,

"Muggering", I think that will catch on. The last post, I think, ol' Uncle
Bill Brooks (4/13/09 8:17 PM) had on this topic raised a concern about "not
having enough resolution in the low impedance area. PV arrays can have an
impedance to ground of a slow as 2kOhms. A resolution of 0.1MOhms will
likely not cut it." Bill went on to say that he had bought a cheaper meter
to test out "for fun".  Some of us do enjoy "muggering around".

So my question is.  Do  the Fluke 1503's and 1507's have enough resolution
in the low range? 

Dave

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Matt
Lafferty
Sent: Tuesday, April 28, 2009 9:56 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] To Megger or not to Megger

RE: Suggested replacements for Fluke 1520 and "pricey meters"... Good News
below!

Another Wrench sent me a note off-list last night, asking how much a
"muggering" would cost. Here's what I sent him:

When I got that 1520 it was just over $600. I just checked online and find
that it's a discontinued item... Bummer! 

Fluke recommends the 1587 or the 1507 or the 1503. They also mention the
1577, but it's an ugly stepsister, or maybe a retarded adopted relative, to
the 1587. 

The 1587 is basically a multimeter that also has a <TEST> button to
discharge a high voltage shock into the sample under test... It runs about
$620 from standard distributors.
<http://us.fluke.com/usen/products/Fluke+1587+1577.htm?catalog_name=FlukeUni
tedStates>
http://us.fluke.com/usen/products/Fluke+1587+1577.htm?catalog_name=FlukeUnit
edStates  You can get it for $522 here: 

 <http://www.testequipmentdepot.com/fluke/megohmmeters/1577_87.htm>
http://www.testequipmentdepot.com/fluke/megohmmeters/1577_87.htm  NOTE: It
does not test at 10A in DMM mode which means it wouldn't be able to test
short-circuit current in strings. Don't bother with the 1577! 

The 1507 & 1503 are more robust equipment. You can check them out here:
<http://us.fluke.com/usen/products/features.htm?cs_id=35391(FlukeProducts)&c
ategory=HMA(FlukeProducts>
http://us.fluke.com/usen/products/features.htm?cs_id=35391(FlukeProducts)&ca
tegory=HMA(FlukeProducts)  While they do measure AC & DC Voltages to 600V as
well as some lower ohm & continuity work, they are really more tailored to
being a megger. The 1503 will suffice for most of what I expect you will get
into, but there are some features on the 1507 that might make it worth
considering. Mind you, I haven't looked at at price on either yet, so that
last comment may just be noises coming out my ass. 

The 1507 has a Compare function which basically sets up a Pass/Fail value so
you can quickly run through repeated tests. This would be useful for doing
larger systems where you are testing dozens or hundreds of circuits at a
time. For my purposes, I want my guys to think a little more than "Buzz =
OK" and I want them to write an actual tested value down on a piece of paper
so this is not a big plus to me.

The 1507 also does Polarization Index and Absorption Ratios. These are more
advanced di-electric tests that you are not likely to need in smaller scale
PV. Use of these features would come into play when playing with real
high-voltage gear or transformers. Might also come into play on
super-sensitive equipment. They might also be used to assess older or aging
underground or overhead feeders. 

The 1507 & 1503 both have an Earth Bond Resistance function which is likely
to become more of an issue in the future. This feature lets you test the
resistance between a grounding electrode or a grounding electrode conductor
and actual earth. Another use for this feature would be to set the output to
1kV, connect the alligator jaw to one of Mike Gripando's extremities and use
the probe lead as a tongue depressor while you push <TEST>. This feature
used to be in a single-purpose tester that ran >$2K. They also both have
backlit displays which comes in real handy out in the field.

The primary features you want are: 500V & 1kV Test Voltage and 2 Gohms
(2,000 Megaohms) or above for the top end of the range. Any of the 3 meet
this spec. 

Well, I just checked prices for the 1503 & 1507 and I'm pleasantly
surprised. The 1503 ranges from about $291-$370. Here's the place I found it
for $291   <http://www.testequipmentdepot.com/fluke/megohmmeters/1503.htm>
http://www.testequipmentdepot.com/fluke/megohmmeters/1503.htm That's marked
down from the regular price of $342.  

The 1507 ranges from about $385 to $500. Here's where I found it for $385...
<http://www.testequipmentdepot.com/fluke/megohmmeters/1507.htm>
http://www.testequipmentdepot.com/fluke/megohmmeters/1507.htm  That's a
special price, for you only, down from $454. 

All things considered if I were in your shoes, I'd go for the 1503. That
give you a solid megger that you can dedicate to that purpose for a
reasonale muggering. If it were me, in Matt's shoes... Oh, what am I saying?
I've already got mine and I just found out I paid too much for it! But I
have Battery Check... Neener neener neener!

Be safe out there!

Matt Lafferty

I hope more hands go up on this topic. Thanks for asking, Keith.

Peace and Palm Trees everybody,

Matt Lafferty

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