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Unformatted text preview: nly with the chassis, modules, accessories, and cables specified in the installation instructions. You must have all covers and filler panels installed during operation of the SCB-68. Do not operate the SCB-68 in an explosive atmosphere or where there may be flammable gases or fumes. Operate the SCB-68 only at or below the pollution degree stated in Appendix A, Specifications. Pollution is foreign matter in a solid, liquid, or gaseous state that can reduce dielectric strength or surface resistivity. The following is a description of pollution degrees: Pollution Degree 1 means no pollution or only dry, nonconductive pollution occurs. The pollution has no influence. Pollution Degree 2 means that only nonconductive pollution occurs in most cases. Occasionally, however, a temporary conductivity caused by condensation must be expected. National Instruments Corporation 1-11 SCB-68 Shielded Connector Block User Manual Chapter 1 Introduction Pollution Degree 3 means that conductive pollution occurs, or dry, nonconductive pollution occurs that becomes conductive due to condensation. Clean the SCB-68 with a soft nonmetallic brush. Make sure that the SCB-68 is completely dry and free from contaminants before returning it to service. You must insulate signal connections for the maximum voltage for which the SCB-68 is rated. Do not exceed the maximum ratings for the SCB-68. Remove power from signal lines before connecting them to or disconnecting them from the SCB-68. Operate the SCB-68 only at or below the installation category stated in Appendix A, Specifications. The following is a description of installation categories: Installation Category I is for measurements performed on circuits not directly connected to MAINS1. This category is a signal level such as voltages on a printed wire board (PWB) on the secondary of an isolation transformer. Examples of Installation Category I are measurements on circuits not derived from MAINS and specially protected (internal) MAINS-derived circuits. Installation Category II is for measurements performed on circuits directly connected to the low-voltage installation. This category refers to local-level distribution such as that provided by a standard wall outlet. Examples of Installation Category II are measurements on household appliances, portable tools, and similar equipment. Installation Category III is for measurements performed in the building installation. This category is a distribution level referring to hardwired equipment that does not rely on standard building insulation. Examples of Installation Category III include measurements on distribution circuits and circuit breakers. Other examples of Installation Category III are wiring including cables, bus-bars, junction boxes, switches, socket outlets in the building/fixed 1 MAINS is defined as the electricity supply system to which the equipment concerned is designed to be connected either for powering the equipment or for measurement purposes. SCB-68 Shielded Connector Block User Manual 1-12 ni.com Chapter 1 Introduction installation, and equipment for industrial use, such as stationary motors with a permanent connection to the building/fixed installation. Installation Category IV is for measurements performed at the source of the low-voltage (<1,000 V) installation. Examples of Installation Category IV are electric meters, and measurements on primary overcurrent protection devices and ripple-control units. Below is a diagram of a sample installation. National Instruments Corporation 1-13 SCB-68 Shielded Connector Block User Manual Parts Locator and Wiring Guide
This chapter explains how to connect signals to the SCB-68. 2 The following cautions contain important safety information concerning hazardous voltages and terminal blocks.
Cautions Keep away from live circuits. Do not remove equipment covers or shields unless you are trained to do so. If signal wires are connected to the SCB-68, dangerous voltages may exist even when the equipment is powered off. To avoid dangerous electrical shock, do not perform procedures involving cover or shield removal unless you are qualified to do so. Before you remove the cover, disconnect the AC power or any live circuits from the SCB-68. The chassis GND terminals are for grounding high-impedance sources such as floating sources (1 mA maximum). Do not use these terminals as safety earth grounds. Do not connect high voltages to the SCB-68 even with an attenuator circuit. Never connect voltages 42 Vrms. NI is not liable for any damage or injuries resulting from improper use or connection. National Instruments Corporation 2-1 SCB-68 Shielded Connector Block User Manual Chapter 2 Parts Locator and Wiring Guide 1 2 3 4 XF1 C6
R22(A) RC12(B) R23(C) RC13(D) R24(A) RC14(B) R25(C) RC15(D) R26(A) RC16(B) R27(C) RC17(D) R28(A) RC18(B) R29(C) RC19(D) R20 R21 C4
S5 S4 S3 R4(F) RC4(E) R5(G) R6(F) RC5(E) R7(G) R8(F) RC6(E) R9(G) R10(F) RC7(E) J1 68 34 67 33 66 32 65 31 64 30 63 29 62 28 61 27 60 26 59 25 58 24 57 23 33 34 R11(G) 13 R38 R30(A) RC20(B) R31(C) RC21(D) R32(A) RC22(B) R33(C) RC23(D) R34(A) RC24(B) R35(C) RC25(D) R36(A) RC26(B) R37(C) RC27(D) RC11(E) RC10(E) RC9(E) RC8(E) R12(F) R13(G) R14(F) R15(G) R16(F) R17(G) R18(F) R19(G) 12 46 13 47 14 48 15 49 16 50 17 51 18 52 19 53 20 54 21 55 22 56 1 3
S1 S2 5 ASSY182470-01 REV.B C2 C1 RC2 R2
RC3 R3 1 35 2 36 3 37 4 38 5 39 6 40 7 41 8 42 9 43 10 44 11 45 6 SCB-68 COPYRIGHT 1993
12 11 10
8 9 10 11 12 13 C5 C3 7 R10 RC1 S/N 8 9
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This note was uploaded on 05/19/2012 for the course ELEN 3030 taught by Professor Joshi during the Spring '12 term at Marquette.
- Spring '12