Fluke 1587 Insulation Multimeter

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mikehughes8 said:
According to 2007 NETA Standards

For cables rated between 0-600V

Minimum Test Voltage 500V

Minimum MegaOhms Reading 500
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Dont think that is right (Actualy neither was my 100M now that I think about it. I thought 500M sounded way high, then 100M seemed high too, so I looked it up.

7.3.2 Cables, Low-Voltage, 600 Volt Maximum
Electrical Tests
1. Perform resistance measurements through bolted connections with low-resistance ohmmeter, if applicable, in accordance with Section 7.3.2.1.
2. Perform insulation-resistance test on each conductor with respect to ground and adjacent conductors. Applied potential shall be 500 volts dc for 300 volt rated cable and 1000 volts dc for 600 volt rated cable. Test duration shall be one minute.
3. Perform continuity tests to insure correct cable connection.
*4. Verify uniform resistance of parallel conductors.
Test Values
1. Compare bolted connection resistances to values of similar connections.
2. Bolt-torque levels should be in accordance with Table 100.12 unless otherwise specified by the manufacturer.
3. Microhm or millivolt drop values shall not exceed the high levels of the normal range as indicated in the manufacturer?s published data. If manufacturer?s data is not available, investigate any values which deviate from similar connections by more than 50 percent of the
lowest value.
4. Insulation-resistance values should not be less than 50 megohms.
5. Investigate deviations in resistance between parallel conductors.
 
izak said:
that megger has voltage sensing capabilities, will function as an ohm-meter (it will show a dead short or resistive load) before you get to push the test button and i dont think it will apply voltage when it senses anything but an open circuit.
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That would be handy, that would be the stupid mistake I would tend to make.
 
Do you have your NETA manual with you! I am positive that the chart in the back says 500 megaohms yet amazingly, I have been wrong before.:smile:
Either way I will double check.
 
Besides disconnecting all loads, disconnecting any GFCI receptacles hasn't been mentioned and pressing the TEST button doesn't solve the issue either.
 
It always coms down to the operator doesn't it ! ? :)
Originally Posted by izak
that megger has voltage sensing capabilities, will function as an ohm-meter (it will show a dead short or resistive load) before you get to push the test button and i dont think it will apply voltage when it senses anything but an open circuit.
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I don't think that is a correct statement based my finite knowledge. :)

George Stolz said:
That would be handy, that would be the stupid mistake I would tend to make.
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For those of you'll that are playing along and not reading the manual on this device Fluke 1577. This is a insulation mutlimeter. This would be alot different testing operations avaiable some are resistance, continuity, Current, + more, all in the same device.
http://assets.fluke.com/manuals/15x7____qreng0000.pdf

Before the machine will allow a test on the insualtion it will if no other test is done...

Unsafe Voltage

To alert you to the presence of a potentially hazardous​


voltage, when the Meter detects a voltage​


≥ 30 V or a voltage overload (OL), the Z symbol is displayed.​



Test Lead Alert


To remind you to check that the test leads are in the​


correct terminals,

​
​
LEAd is momentarily displayed when you

move the rotary switch to or from the c position.​

Warning​


To avoid a blown fuse, damage to the Meter,​


or serious personal injury, never attempt to​


make a measurement with a test lead in an
incorrect terminal.​


​
​
​
​
​
​



​
 
mikehughes8 said:
Do you have your NETA manual with you! I am positive that the chart in the back says 500 megaohms yet amazingly, I have been wrong before.:smile:
Either way I will double check.
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I have the 2001 MTS and the 2003 ATS on my smart phone, so I can pull them up anytime, the 2007 versions I only have hard copies and they are at work, but I dont think they changed anything for LV cables. I could be wrong too, wouldnt be the first time.
 
Bob, I dont know any real specs but, the majority of the readings we get with that meter is >2.2g (meter infinite) within 15 or 20 seconds

thats nearly Always true with new wire just pulled in (assuming all the ends are dry, nothings touching, laying on concrete blah blah blah)

I tested some old RW that was installed in the 50s that tested down around 300M and some THHN that was about 6 or 7 years old that wouldnt go over 1.1G, but by and large, if you just put it in, its gonna max out.

except for that one time with the 500 Kcmil Southwire NO-Lube... it tested no higher than 36M.

we pulled it out. there was nothing obviously wrong with the jacket so, we sent it back.
 
mikehughes8 said:
I was able to find this for the Pearl reconditioning standards which is in most cases a reproduction of NETA standards.
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Umm, no they are not, not at all, I am a member of both and am active on commitees with both orgs, they are apples and oranges, those standards have very little to do with each other. Where are you getting all of these "facts"?

mikehughes8 said:
I did a megger test on a medium voltage cable at 5000V the other day and the minimum value required was 5000Megaohms.
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Sure, I hope that is not the only test you did. Megger test on MV cables dosent tell you much, only if it is safe to perform your dielectric strenght test (Overpotential)
 
When shipboard, we routinely performed megger tests. I recall a Biddle instrument that had a guard terminal or such that allowed our section leader to clamp one lead to one end a small fluorescent lamp, the other lead in his hand and the other hand on the opposite end of the lamp to complete the circuit. He would turn off the space lighting and ask a machinist mate to crank the instrument. The lamp would glow dimly yet impressively.

The next step was to switch the leads off safety, loan the instrument and lamp to the machinist mate and watch him step off to impress his mates. From the adjacent compartment came the sounds of the screaming machinist and breaking glass. The machinist returned the megger with a few choice words about crazy electricians liking getting shocked!
 
jeremysterling said:
When shipboard, we routinely performed megger tests. I recall a Biddle instrument that had a guard terminal or such that allowed our section leader to clamp one lead to one end a small fluorescent lamp, the other lead in his hand and the other hand on the opposite end of the lamp to complete the circuit. He would turn off the space lighting and ask a machinist mate to crank the instrument. The lamp would glow dimly yet impressively.

The next step was to switch the leads off safety, loan the instrument and lamp to the machinist mate and watch him step off to impress his mates. From the adjacent compartment came the sounds of the screaming machinist and breaking glass. The machinist returned the megger with a few choice words about crazy electricians liking getting shocked!
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We used to megger MM's, and basicly all other non electrical rates (Besides the cooks, never mess with the cooks on a submarine), set traps and meggered them all the time. However, as a safety professional I can no longer condone such sophmooric actions.
 
LOL, the meter came directly to me so I have all the literature that came with it.
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"LOL"... thought you might :D

iwire said:
But before I go digging into the instructions I figured I could get some tips here .... and I have. :cool:
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I got that impression... hence my post :wink:

iwire said:
Mostly what I am wondering about the readings I should be getting back on good conductors. :smile:
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As izak wrote... typically, meter infinity on new installations, which is, according to the manual...
"When resistance is higher than the maximum display range, the Meter displays the > symbol and the maximum resistance for the range."​

First issue if you do get a reading that is less than max, will be to determine if it is a false-positive [such as inadvertent non-isolation of conductor(s) under test]. It is only when you verify a true positive that you even become concerned.
 
zog said:
2. Perform insulation-resistance test on each conductor with respect to ground and adjacent conductors. Applied potential shall be 500 volts dc for 300 volt rated cable and 1000 volts dc for 600 volt rated cable. Test duration shall be one minute.......
Test Values.....

4. Insulation-resistance values should not be less than 50 megohms.
Click to expand...


Thanks Zog.
 
Sure, I hope that is not the only test you did. Megger test on MV cables dosent tell you much, only if it is safe to perform your dielectric strenght test (Overpotential)
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I meggered (DC insulation resistance test) a MV cable that had just been terminated with dead breaks breaks. The purpose of the test was to identify any gross fualts in the dead breaks or cable as a result of workmanship before putting them it into service. The cable itself was put through acceptance testing when it was recieved.
So to say the megger test has no other purpose other than to tell you if a follow on test is safe is complete nonsense no matter how many boards you sit on.



As for as the Pearl Reconditioning standards go if you go to the web site listed in my previous post. At the bottom of many of their tables it says "Reproduced from NETA MTS – 1997 Table 10.14"

Fixed UBB Code
 
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mikehughes8 said:
So to say the megger test has no other purpose other than to tell you if a follow on test is safe is complete nonsense no matter how many boards you sit on.

Fixed UBB Code
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You arent even meggering at the system voltage level on a 15kV cable, how can you call that a sufficient test? I have worked with a lot of Prime Power guys, and while it is a good program you will see when you get out that the Army only touches the tip of the iceberg for testing requirements. Look at your NETA tests for MV cables, see what all is required.
 
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