erby@alchemy.tcnet.ithaca.ny.us (Michael Erb) (04/15/91)
MEI/Micro Center is selling a "3 Mode Full Protection 6-Outlet
Spike/Surge Supressor with Modem/Fax & EMI/RFI protection" for
$15.95.
I'm wondering if the specifications indicate whether this device
is worth it. Any feedback concerning these specs or just more
general information on what to look for in a surge protector
would be appreicated.
Here are the published specs
Surge Supression Specifications:
Clamping Voltage-460v
Max. Spike Current-4500 AMPS
Max. Surge Dissipation-54/162 Joules
Clamping Response Time-.8 Nanoseconds
Modem Sepcifications
Joules-20
Clamping Voltage-140v
Current Peak-1200 AMPS
Are these typical specifications for a surge protection device?
Mike Erb
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E-Mail: Erby@Alchemy.tcnet.Ithaca.NY.US(Michael Erb)
USPS : Michael R. Erb
PO Box 6770
Ithaca, NY 14851-6770
Phone : (607) 277-4326
******************************************************majeske@remus.rutgers.edu (Joseph Majeske) (04/16/91)
Michael erb writes: >MEI/Micro Center is selling a "3 Mode Full Protection 6-Outlet >Spike/Surge Supressor with Modem/Fax & EMI/RFI protection" for >$15.95 ... >if the specifications indicate whether this device is worth it I can speak to that, as I just got one last week. Yes, the _specifications_ indicate that this device is worth it. The device, however, fails to conform to the specifications. Usually I buy a six-outlet strip and add my own filters and MOVs, but since that price was only a little higher than a plain vanilla power strip, I thought I'd give it a try. "3 Mode Full Protection" in the usual sense, means that the device protects against common mode surges (those between hot & neutral), and surges between hot and ground, and neutral and ground. Typically in low end surge suppressors this is done by a metal oxide varistor between each wire. The MEI device does have 3 MOVs, but all of them are used in a bridge between hot and neutral. It does not protect against the other two modes at all. I am going to add 2 additional MOVs and a better filter. In short $15.95 buys a nice box. Not to denigrate the box, I like the box, but full protection it is not. Doubtless they would say that they mean Spike/Surge, EMI/RFI, and phone protection by "3 Mode Full Protection." This is not the first time I have encountered false claims in cheap surge suppressors. The only way to be sure is to open the box. Look a for thing that looks like a large disc capacitor soldered between each of the three wires (the MOV). Or buy an expensive and reputable brand like ISOBAR. In no case should you ever buy a surge suppressor from Radio Shack, the Technology Store from Hell(tm). Every RS suppressor I have encountered had a false label. I have no connection with ISOBAR or (ack! ack!) Radio Shack.
wnn@ornl.gov (04/16/91)
In article <Apr.15.17.27.22.1991.20480@remus.rutgers.edu> majeske@remus.rutgers.edu (Joseph Majeske) writes: >Usually I buy a six-outlet strip and add my own filters and >MOVs... You seem to understand what your are talking about. We have a couple of old suppressor boxes that seem to have gone bad. Can you give us any specs and sources for filters and MOVs to replace/upgrade? How are the phone line surge suppressors wired? How good are MOVs really, how long can one expect them to last/ how do you tell they are bad or no longer adequate? I read some time ago, that good surge suppressors use Multi Function Ceramics (MFCs) instead of MOVs, because they do not degrade over time. Is that true? Where do you get MFCs (specs)? Are they wired just the same as MOVs? Answers from you or someone else with an EE background in this area would greatly be appreciated. Wolfgang N. Naegeli University of Tennessee & Oak Ridge National Laboratory Internet: wnn@ornl.gov Bitnet: wnn@ornlstc Phone: 615-574-6143 Fax: 615-574-6141 (OrchidFax) QuickMail (QM-QM): Wolfgang Naegeli @ 615-574-4510
majeske@remus.rutgers.edu (Joseph Majeske) (04/18/91)
wnn@ornl.gov (Wolfgang N. Naegeli) writes > Can you give us any specs and sources for filters and MOVs to > replace/upgrade? I have received five or six queries on this subject. In a couple of days I will compose and post an article containing everything I know about surge protection. > I read some time ago, that good surge suppressors use > Multi Function Ceramics (MFCs) instead of MOVs, because they > do not degrade over time. Is that true? MOVs degrade with use, true, but I am not familiar with MFCs. If someone knows about these please post, or mail me and I'll summarize.
erby@alchemy.tcnet.ithaca.ny.us (Michael Erb) (04/20/91)
Assuming I do not exceed the recommended total load of the supressor, in
my case 15 amps, is it safe to plug a plain power strip into one of the
surge supressors outlets in order to add and protect additional
equipment? It would seem to me that it would be safe to do this as the
supressor is simply going to "do its thing" with little regard to what is
plugged into it. Any feedback is appreciated.
Mike
******************************************************
E-Mail: erby@alchemy.tcnet.ithaca.ny.us (Michael Erb)
USPS : Michael R. Erb
PO Box 6770
Ithaca, NY 14851-6770
Phone : (607) 277-4326
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