Electronic circuit terminal blocks offer several different functions, including voltage indication, over-voltage protection, kick-back protection and polarity-reversal protection. In addition, a prototyping terminal block circuit board is available that enables the end user to test out a new design or to prototype a circuit board for later production built by the company. The current bar for the screw-clamp terminal blocks is surface-mounted to the PCB and the electronic components can be either surface-mount or through-hole devices. Automation Systems Interconnect Inc. (ASI), Carlisle, Pa.
Hybrid Terminal Blocks
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The QTS 1.5/4 and 2.5/4 are hybrid terminal blocks that reportedly incorporate an IDC connection on one side and a more conventional spring-clamp mechanism on the other side. The blocks are designed for panel builders who cannot monitor the wiring of the panel in the field. The 1.5/4 accepts a 22 to 16 AWG wire on the IDC side and 24 to 10 AWG wire on the spring side. The 2.5/4 accepts 24 to 10 AWG wire on the spring side and can handle 18 to 14 AWG wire on the IDC side. Phoenix Contact Inc., Harrisburg, Pa.
Dual-entry Plugs
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CVF Left and Right Plug Series plugs are designed to offer higher voltage ratings for flexibility in design considerations and/or replacement use. Ratings for either the left- or right-hand version are at 12 A at 300 V or 12 A at 450 V. Standard pin spacing for all styles is at 5.00 or 5.08 mm. Available in two to 25 positions in a single mold, wire entry can be from either side, which is said to provide usage flexibility. BlockMaster Electronics Inc., Elk Grove Village, Ill.
Pluggable Terminal Blocks
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The 3.50 and 3.81 mm Pluggable Terminal Blocks offer plug and header styles, including a screw-flange and threaded-insert connection version. Applications include security systems, HVAC, industrial equipment and instrumentation. All configurations are available in two through 25 positions; however, screw-flange/threaded-insert configurations are available in two through 23 positions. AMP, a part of Tyco Electronics Corp., Harrisburg, Pa.
PCB Terminal Blocks
The company's line of PCB terminal blocks includes multipole terminal blocks from two to 36 points with pin spacing from 0.138 to 0.600" (3.50 to 15.24 mm). Power terminal blocks with pin spacing from 0.250 to 0.500" (6.35 to 12.70 mm), featuring current to 45 A, are UL/CSA-rated to 600 V, 20 to 6 AWG. Additional terminal blocks include quick-connect blocks and barrier strip terminal blocks in 10- and 20-pole models. Entrelec Inc., Irving, Texas
Custom-manufactured Terminal Blocks
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The company designs and produces terminal blocks to meet customers' needs. The 10-line custom PCB connector, produced for a manufacturer of numerical and programmable controllers, has 0.375 centers, bifurcated leaf connectors and a body made of UL-listed thermoplastic. Custom Connector Corp., Cleveland, Ohio
Power Distribution Blocks
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SnapBlocks are modular power distribution blocks. The design is said to handle multitap and feed applications, reportedly covering virtually any requirement. The products snap together and lock into place without tools. Dual-rated, they are available in 24 connector styles for conductor sizes #14 to 500 MCM and can be used with any combination of aluminum or copper conductors. ILSCO, Cincinnati, Ohio
Terminal Block
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The PM 5.08 leaf spring terminal block has a size range of 22 to 14 AWG, and is UL-rated for 300 V and 10 A. It is available in two- and three-pole versions that can be dovetailed up to 16 poles. Also offered is a marking area that can accommodate either marking strips or pad printing in either black or orange. It is made from polyamide 66, a nylon molding material with a UL 94V-2 flammability rating. Weidmüller Inc., Richmond, Va.
Terminal Blocks
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DIN rail-mountable and PC card-edge Eurostyle terminal blocks are available. PCB-mount products are available in both screw-terminal and spring-clamp termination types. The spring-clamp technology, a quick termination system, reportedly is suitable for use in harsh environments and high-vibration areas, and can withstand corrosive element exposure or extreme temperature fluctuations. The DIN rail-mountable products also are available in screw-terminal and spring-clamp types. PTR Connex, a Phoenix Mecano Co., Frederick, Md.
Ceramic Terminal Blocks
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This series of ceramic terminal blocks is designed for industrial, process equipment and machinery applications with strict temperature and space requirements. Said to be compact and durable, Euroblocks reportedly provide wire connections in high-temperature environments. They are offered with mounting holes to enable panel-mount or free-float applications. One-, two- and three-pole terminal blocks are available in 4.0, 6.0 and 16.0 mm2 wire sizes. Altech Corp., Flemington, N.J.
Modular Terminal Blocks
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Horizontal and 45° entry, modular, PCB-mount terminal blocks are designed for use on high-density PCBs. The 45° entry blocks reportedly feature easy-access termination points and are constructed with screw heads on the top to facilitate access. Both designs are available with two and three terminal positions that can be interlocked to a maximum of 24 positions. Termination points are said to have a wire guard that helps prevent damage to conductors. Keystone Electronics Corp., Astoria, N.Y.
DIN Rail Terminal Blocks
The design of the taris IDC Series of terminal blocks is said to reduce wiring installation time and labor, especially in high-volume wiring applications. Its features include a UL 94V-0 nonflammability rating on the polyamide 6.6 insulator, marking tag facilities at each termination point, built-in test points, single and dual push-in jumpering slots, and nickel-plated copper alloy contact material. The 5 mm blocks are rated for 600 V, 15 A and 22 to 16 AWG; the 6 mm blocks are rated for 600 V, 25 A and 18 to 14 AWG. Wieland Electric Inc., Burgaw, N.C.
Spring-clamp Terminals
These spring-clamp terminals are for connecting proximity switches and sensors. Part No. 35370/2 is a distribution terminal that is 5 mm wide, accepting up to 14 AWG wire. The power is distributed via a plug-in bridge. Terminals can be stacked to accommodate a number of sensor and proximity switches. Terminals with internal ground bar are also available. Woertz - USA, Colmar, Pa.
TECHNOLOGY UPDATE
By Anita Black
The International Electrotechnical Commission (IEC) terminal block has followed a similar evolution to that of the connector industry, which has a technology path that includes soldering of wires for connections to crimping of wires for connections to insulation displacement connection (IDC). Today as this connection technology continues to evolve, the preferred method of terminating a wire in the industrial market remains the basic screw-clamp type of terminal block. However, now the customer has the option of selecting the connection technology that best suits the application.
For flexibility, ease of use, a range of wire sizes, and multiple circuits and functions, the screw-clamp type of terminal block connection offers the best option for providing a solution. In applications where wire size, vibration, panel space and other issues do not present a problem, the spring-clamp type of terminal block connection may be the technology of choice. Finally, the insulation displacement type of terminal block technology is becoming the choice in control circuit applications where wire size is known and limited in size and where speed and labor savings are required. The customer now has a level of flexibility in terminal block selection equal to that of connectors and can select the most ideal method of wire termination to fit the current application and environment with screw-clamp, spring-clamp and IDC terminal blocks.
Because of the fact that every application is different, engineers need a choice in interconnect and interface technology. The evolution of IEC terminal block wire termination technology will continue to inspire the development of innovative product offerings in order to meet these changing needs of the customer. Still growing, the variety of terminal blocks combined with a wide range of connector interface modules provides a choice to design engineers that addresses any application, including the method of wire termination.
ANITA BLACK is communications manager, Automation Systems Interconnect Inc. (ASI), P.O. Box 1230, Carlisle, PA 17013; (717) 249-5581; Fax: (717) 249-5542; E-mail: ablack@asi-interconnect.com; Web site: www.asi-interconnect.com.
