CORD GRIPS » EMI / RFI Cord Grips

How They Work

How TOR-SPRING™ Cord Grips Work

The key features of TOR-SPRING™ Cord Grips are a unique Toroidal Spring, which is made using advanced manufacturing methods, and (2) precision machined Tapered Retaining Rings. The Toroidal Spring is positioned between the Retaining Rings and when the Dome Nut is tightened, the Cord Grip's Insert presses the Tapered Rings together, altering the shape of the Toroidal Spring and forcing it against the circumference of the Braided Shield. (See Figure #2) This action places the spring in direct contact with the shield around its entire circumference, providing full 360° EMI/RFI Protection of the cable. Because the Tapered Rings are in direct contact with the Cord Grip Body, a continuous low resistance, ground connection is made from the cable shield to the enclosure/housing structure. Lastly, because the cable's Braided Shield does not have to be cut and removed when installing TOR-SPRING™ Cable Grips, it provides continuous EMI/RFI shielding from the Cord Grip attachment point to the internal termination point. This condition eliminates the need for specification and installation of time consuming and costly secondary shielding for this length of cabling.

Note: Secondary shielding is an extremely critical requirement when using traditional design EMI/RFI Cord Grips because unshielded control and data cabling inside an enclosure/housing can be directly affected by the harmful electromagnetic emissions contained within the structure. Subsequently, the entire system's EMC Integrity could be compromised if this run of cabling remains unshielded.

TOR-SPRING™ Cord Grip Shielding Principle Tightening the Dome Nut (1) causes the Cord Grip Insert (2) to press against the Tapered Rings (5A and 5B), which in turn, alters the shape of the Toroidal Spring (6) forcing it against the circumference of the cable's Braided Shield (See Figures #1 and #2). The resulting continuous ground potential is provided to the enclosure/housing from the Braided Shield through the Toroidal Spring and Tapered Rings to the Cord Grip Body which is secured to the structure by a Locknut. Tor-Spring™ Cord Grip Components 1. Dome Nut 2. Insert 3. Body 4. Seal Ring 5. Tapered Rings 6. Torodial Spring As Dome Nut is tightened, the Torodial Spring Deforms, Tapered Rings close When Dome Nut is loose, Tapered Rings are open, Torodial Spring unchanged Figure 1 Figure 2

TOR-SPRING™ Cord Grip EMI/RFI Shielding Performance When properly installed, traditional ring design Cord Grips provide acceptable EMI/RFI Shielding Performance. Conversely, when installation instructions are overlooked or not followed closely and an improper installation occurs, shielding attenuation values are subject to significant variation and in some cases can be inadequate. Because the design of TOR-SPRING™ Cord Grips is based on the toroidal spring/tapered ring principle that involves a simplified, modern installation method, EMI/RFI Perform- ance is not influenced by installation variables. The TOR-SPRING™ Cord Grip's shielding attenuation results are extremely consistent and repeatable from installation to installation This predictability affords the designer confidence that planned control of EMI/RFI Interference will be realized. A representative example of the TOR-SPRING™ Cord Grip's excellent shielding characteristics is found in the graphical attenuation data presented in Figure #3.