Thinking about getting a megger

Wade C · Aug 8, 2018

I have a servo drive that went out, and from talking to the tech, I can probably get a megger for less than the cost of a service call to get the motor checked before I replace/repair the drive (Okuma BLII-D 50amp).

So thought I would see if anyone has a recommendation on what might a decent brand that wont break the bank for something that I just wont use very much?

I like Fluke, but cant justify 600-900 for theirs... Hoping in the 100-200 range for something halfway decent. Thoughts or suggestions?
Thanks
Wade

BugRobotics · Aug 8, 2018

Hi Wade, I can loan you mine. I’m in Denver.

hermetic · Aug 8, 2018

Get an old school wind the handle type! If you can get a genuine "Megger" made by Evershed and Vignoles in London, you will not go far wrong. The Fluke gear is now virtually all made in China, and average life is about 5 years, after which time the meter will be no longer able to be calibrated! Ask me how I know! My Megger is about 40 years old and in perfect working order, and if you look inside one, you can tell why they were so expensive when new!

Wade C · Aug 8, 2018

Hmmm.... sounds like more I have to learn about :P

Bug Robotics - Ill send you a PM
Wade

Fulcircleny · Aug 8, 2018

Cant you power down, swap the axis drive cards, top and bottom? if it is the electronics the problem should migrate with the board.
the risk, the second board may blow if it isn't the card. you can see the LEDS on the lower right of the card, they all green, as the should be? When the BLD 50card blows that is the fault you get on the screen. I use a place on North Carolina to repair the board when they blow. either way good luck
Chris

Wade C · Aug 8, 2018

Fulcircleny said:
Cant you power down, swap the axis drive cards, top and bottom? if it is the electronics the problem should migrate with the board.
the risk, the second board may blow if it isn't the card. you can see the LEDS on the lower right of the card, they all green, as the should be? When the BLD 50card blows that is the fault you get on the screen. I use a place on North Carolina to repair the board when they blow. either way good luck
Chris

X and Z servo drive is one unit... doesnt have two separate drives (1995 LNC-8)... My concern is tech said that though unlikely - possible the the motor took out the drive. So id really rather not spend thousands twice if I can avoid it and check the motor first without breaking the bank in the process (as the servo drive may do that on its own the first time). And it seems I am that guy... the one that ends up with the out of the ordinary situations... so just trying to hedge my bets rather than risk components, money and additional down time.

Ive spoken with my Okuma tech (he is the one that suggested megging out the motor) and sent pics of all the lights on the drive as well as alarm numbers... Pretty much the drive is bad... lots of red lights on and got 201-4 Z axis alarm before shut down, and then 65 P-alarm at boot up. Sounds like its a matter of spending 6k on a new one or 2k to repair this one and have a few new bits put in with the old ones to make it run and still have lots of old bits n pieces. :scratchchin:

Got a megger coming so will meg out the servos and see where things are before I go sticking anything new, used, or repaired in there

Wade

BugRobotics · Aug 8, 2018

I'd probably test the cables going to the servos as well. Not sure about the cable routing/protection in your Okuma but if the cable can rub against anything it's possible that the cable is damaged. Just make sure they are disconnected from everything before testing.

Wade C · Aug 8, 2018

Yep! Gonna do just that!

atomarc · Aug 8, 2018

As Mr. Bug pointed out, disconnecting the motor from the drive is very important. The oink the megger puts out can kill all kinds of stuff.

Stuart

Wade C · Aug 8, 2018

For sure!! Just got off the phone with the tech and got walked through it... SHould be fairly uneventful - I hope

Thanks!
Wade

atomarc · Aug 8, 2018

Wade,

I'm not well versed in servo motors, but what are you expecting to find with the megger? A simple Ohmmeter will tell you quite a bit in regards to opens and shorts although it won't hit the insulation with a jolt like the megger will. Is that what you're searching for, a leak in a winding?

Stuart

Wade C · Aug 8, 2018

Okuma tech said to meg it out to make sure the motor didnt blow the drive... I didnt ask further. Just figured if running an ohmeter across it was good enough, he'd have me do that rather than suggest to meg it out.

Im basically just chicken at this point - and have more time than money right now... if an extra day or two waiting for the megger to get here insures I dont blow up the replacement servo drive... its insurance Ill be willing to pay at this point in time. Sure, I wish I was running parts right now instead of chasing parts... but a few days waiting for the megger to get here and install the drive - and back to running seems more palatable than pay for one drive, then finding out it was the motor and then getting a motor and another drive...

Wade

Strostkovy · Aug 8, 2018

Use a regular meter first. If it's taking out the drive a regular meter will probably catch it.

thermite · Aug 8, 2018

Wade C said:
I have a servo drive that went out, and from talking to the tech, I can probably get a megger for less than the cost of a service call to get the motor checked before I replace/repair the drive (Okuma BLII-D 50amp).

So thought I would see if anyone has a recommendation on what might a decent brand that wont break the bank for something that I just wont use very much?

I like Fluke, but cant justify 600-900 for theirs... Hoping in the 100-200 range for something halfway decent. Thoughts or suggestions?
Thanks
Wade

Megger IS a "brand".

Electrical test, maintenance & measurement products | Megger

Pioneered the uber-sensitive hard-to-measure field with gawdawful costly "Megger Earth tester" about a thousand years ago. Telcos and Utility firms, their contractors, their military counterparts had them. We had no other good choice.

Megger NOW makes a LOT of specialized instruments. I'd want a budget in the $1,000 and UP range, not $100-$200, if I needed that. They command prices well ABOVE Fluke, not below.

Many of Megger's classical tasks can now be done with top-end, but otherwise general-purpose goods instead.

You probably do NOT need any of it, though. You don't need to know "how bad" a component is. Only whether or not it is bad at all. Substitution/swap, as already suggested, is good enough.

Wade C · Aug 8, 2018

I guess I should clarify then... something to "meg out" as Ive been told, a motor. For the short term, I have been able to borrow one... so that will get me by, but Im tempted to find something in the less expensive but workable line. Fortunately, not needing one immediately since I was able to borrow one (should be here in a couple days) that will allow me to spend more time looking and learning. Just shy of the 50 - 80 dollar ones a guy sees on amazon and the like...

Ill run an ohm meter leg to ground and see where it comes in... but will double check it with the Megger that I was lucky enough to borrow. Its all a learning experience for me... hopefully I come out the other end smarter

Thanks

TDegenhart · Aug 8, 2018

First thing is don't confuse a megger with a hipot tester. A megger is designed to measure the resistance of an insulating system without damage to the system. A hipot machine is also used to check for insulation at a high voltage, but if there is a failure, the system can be damaged. Hipots are used as a pass/fail test.

The other issue do you want to invest money into an instrument that you may only use once or twice in a ten year period? That's about how often I use my hipot. I have one because it was given to me years ago.

Tom

JST · Aug 8, 2018

1) You DO want to use the megger, and not the meter, because faults are very often voltage sensitive. It can check out good at 3V with the meter, but with the full 360V on it, plus spikes, it may be nearly a dead short.
The megger will find that, and will not ignore regular shorts, it does both.

2) As for buying the tester, I'd not unless you expect to need it more often. If you can get the use of one, that should do the job for you.

BTW, they can knock you on your ass, they put out a good jolt. So watch out, and have everything set in a good solid position when you do tests, so you are not juggling equipment and test leads.

thermite · Aug 8, 2018

JST said:
If you can get the use of one, that should do the job for you.

BTW, they can knock you on your ass, they put out a good jolt.

+1 They were often rented. AS OFTEN.. we'd hire a firm with a tech already expert with it to bring one and do the do, Earth testing especially. We got a valid third-party chit that way.

This case, I still say swap it and see FIRST.

In general, whenever one CAN do, actually.

jim rozen · Aug 9, 2018

Biddle makes a tolerably good hand-crank megger.

Another approach if you serious about this, is to buy a used
General Radio high voltage ohmmeter.

Pathogen · Aug 9, 2018

I learned of Banggood on this site, source for inexpensive quality stuff from China. They have three meggers under $45 that will do the job of US made ones that cost $1000

Should get one to call your own

Thinking about getting a megger

Stainless

Stainless

Hot Rolled

Stainless

Cast Iron

Stainless

Stainless

Stainless

Diamond

Stainless

Diamond

Stainless

Titanium

Diamond

Stainless

Diamond

Diamond

Diamond

Diamond

Hot Rolled

Similar threads