Transc.21-216Protective earthscrew (or anyscrew with a goodearth connection)Make sure the boxes areproperly earthed with shortestpossible connections to, forexample, an earthed frame< 10 m between earth pointsFor ”soft earth”remove jumper P4R = 100 kohmC = 100 nFTransceiver 21-216 and PCM should preferably usethe same auxiliary voltage supply (a 48 V battery)Directearth(default)Outer shielding connected toearth at both endsInternalelectronicsInternalelectronicsdirectly earthedIEC08000073-1-en.vsdxPCMIEC08000073 V1 EN-USFigure 76: Earthing principlesP4IEC10000207-1-en.vsdxIEC10000207 V1 EN-USFigure 77: Earth selector jumperThe strapping area/jumper P4 selects how internal signal earth and chassis earth arereferenced together. With a jumper between P4's terminals, signal earth and chassis earth aredirectly connected. Without a jumper between P4's terminals, signal earth and chassis earthare connected with a 100 kΩ resistor in parallel with a 100nF capacitor.After jumper selection, reassembling is done in the reverse order to above. Do not forget toreconnect protective earth cables.5.5.7 Communication structure for laboratory testingGUID-A1B07E54-B7A3-40E1-85A0-61AA17D03398 v1During laboratory testing, one transceiver 21-216 has to provide the timing. This is done byremoving the jumper on its S14 EXT CLK. Remember to restore the jumper after testing.Section 5 1MRK 505 382-UEN ECommunication set-up76 Communication set-up, 670/650 seriesApplication Guide© Copyright 2017 ABB. All rights reserved
