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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
Posted to alt.engineering.electrical,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
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Fluke DMMs and VFD motor drives
DaveC wrote:
I'm considering the purchase of a new Fluke DMM. I like the low-impedance feature of the 117, but the low-pass filter feature of the 87 is also attractive. I had a conversation with a support engineer at Fluke today to try to help me decide between these two meters. It came down to the question of whether the variable-frequency drives I come across will have noisy outputs which the low-pass filter will be helpful in dealing with. Among other services, I install some (3-phase, mostly) VFDs for 230v motors on old printing equipment to give them a 2nd life. I have no idea how many (ie, percentage) of VFDs are "noisy" that will make measurement difficult with a DMM w/o low-pass filtering. Is this a common problem? If you've got some experience in this area I'd like to hear your comments. Thanks, Dave A scope meter is the best tool for such a job.. |
#2
Posted to alt.engineering.electrical,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
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Fluke DMMs and VFD motor drives
A scope meter is the best tool for such a job..
[Jamie] Why? Also, I already have a hand-held scope (Tektronix) so I don't want to spend $$ unnecessarily on features I already have in maybe another tool. Dave |
#3
Posted to alt.engineering.electrical,sci.electronics.design,sci.electronics.equipment,sci.electronics.repair
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Fluke DMMs and VFD motor drives
DaveC wrote:
A scope meter is the best tool for such a job.. [Jamie] Why? Also, I already have a hand-held scope (Tektronix) so I don't want to spend $$ unnecessarily on features I already have in maybe another tool. Dave Because working with VFD's, especially with Vector mode drives, You see a lot more happening in the output over what a DMM can show you. Even my Fluke 289 with it's low pass will give incorrect readings of what is really happening if a Vector drive isn't tuned, incorrect induction values, defective encoder, something etc.. If all you're looking for is a ball park figure, then I guess you could use a low pass DMM. It's up to you. For every man, they have their own tool! |
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