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Measurement Testing
A Resource Dedicated to Environmental Testing, EMC Testing, Vibration Testing and related areas
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Mjr
Site Admin
Joined: 13 Jul 2005
Posts: 294
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 Posted: Fri Dec 02, 2005 10:07 am Post subject: EMI-shielded conduits |
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ZERO GROUND offers three NEW types of flexible liquidtight conduits designed for wiring applications requiring shielding effectiveness from Electromagnetic and Radio Frequency Interference (EMI / RFI).
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This series of shielding conduits consists of three configurations:
LAS – Good Shielding
EMS – Better Shielding
EMSP – Best Shielding
These conduits are used to protect sensitive electronic circuits such as communications, radar, and data transmission from outside interference or "noise". The reverse situation is also an issue. Today's Original Equipment Manufacturers (OEMs) are finding that, if they wish to ship electrical equipment into the European community, they may need to be in compliance with the European CE standard, which reduce the allowable amount of EMI/RFI emissions from electrical apparatus. Complete specifications (shielding effectiveness, flexibility, bend radius, reel lengths, weights etc.) are available upon request.
All three are designed to accept industry standard liquidtight connectors (ZERO GROUND recommends Thomas & Betts T&B fittings) and address the problems of assembly and grounding. Connectors of this type include a grounding ferrule, which contacts the internal metallic material of the conduit and the connector body. This produces a direct shield-to-drain or ground, simply by tightening the connector.
The graph and chart below depict the shielding effectiveness (attenuation in dBs) of all three types. The dotted line (graph) shows a comparison to standard unshielded liquidtight flexible conduit type LA. The spectrum of test frequency is from 1 MHz to 10MHz Electri Field, to 100 MHz to 1 GHz (1000 MHz) Planewave Field. Tests were performed per MIL-STD-285 on 1/2" trade size conduit.
All conduits meet NEC 350 Liquid Tight Flexible Metal Conduit Type LFMC. |
Example:
TYPE - LAS
Type LAS is identical to standard UL Listed liquidtight flexible steel conduit, but is augmented with a tinned copper shielding braid located over the inner steel core and under its protective PVC jacket. The braid offers a minimum of 90% coverage resulting in a shielding effectiveness range from 126dB @1 MHz to 66 dB @ 1GHz.
APPLICATION:
-This Conduit is intended for installation in accordance with Article 350 of the NEC (ANSI/NFPA-70)
-Suitable as an equipment grounding conductor per Article 250.118(7).
-Suitable for use in Hazardous Locations: Class I, Div. 2 and Classes II and III.
-PVC jacket is resistant to a wide variety of Oils, Acids, Alkaline and Ultraviolet Light. Polyurethane Jacket (ZHLAS) available.
-Accepts Standard Liquidtight Fittings
TYPE - EMS
Type EMS has an inner core that is made from a fully interlocked bronze strip. Even though it does not contain a braided shield, it offers a shielding effectiveness from 126 dB @ 1MHz to nearly 100dB @ 1GHz. ZERO GROUND has compatible metallic brass (nickel-plated) fittings available for this bronze conduit.
Contact Zero-Ground for more info:
http://www.zero-ground.com
866-ZERO-GND (toll-free)
866-937-6463 (toll-free) |
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