Instrumentation and Control Surge Protection Protecting discrete digital signals using the PLUGTRAB PT 4X1… and PT 2X1… TRABTECH Application Note 2555A 1 © PHOENIX CONTACT - 04/2009 Description Digital input/output (I/O) signals can be protected using the PLUGTRAB PT 4X1… and PT 2X1. The PT 4X1 can protect up to four discrete/digital signal circuits while the PT 2X1… can protect up to two discrete/digital signals. The PLUGTRAB is installed in one of two base elements: the PT…+F-BE base provides isolation between the shield and ground while the PT…-BE base bonds the shield to ground. The bond in the PT…-BE base provides a drain for noise collected on the shield. Using the PT…+F-BE base prevents unwanted ground loops by isolating the shield and ground. The most common applications use the PT-…-BE base. 11 9 5 3 7 1 Input 12 10 6 8 4 DC Common 2 OUT IN + – Power Supply Figure 3. Typical Input Wiring for PT 2X1-BE Base Position Indicator Indicator Lights Relays 11 9 5 3 7 1 Input Input Input 12 10 6 8 4 DC Common 2 OUT IN + – Power Supply 11 9 5 3 7 1 IN Output Output 12 10 6 8 4 2 OUT Figure 1. Typical Input Wiring for PT 4X1-BE Base Figure 4. Typical Output Wiring for PT 2X1-BE Base Position Indicator Indicator Lights Relays 11 9 5 3 7 1 IN 12 10 6 8 4 2 OUT Output Output Output +24 V DC – – + Power Supply Output Figure 2. Typical Output Wiring for PT 4X1-BE Base +24 V DC – + Power Supply Instrumentation and Control Surge Protection 1.1 Proper Grounding During a surge event, energy can come from several signal cables. If multiple PLUGTRABs are used to protect different signal lines, they will all divert the surge energy to the ground, via the DIN rail. This energy needs a low impedance path to ground. A grounding wire the same size as the power ground wire ensures low impedance. The PLUGTRAB prevents surge energy from reaching the control equipment by diverting this energy to the ground circuit. Figures 5 and 6 show a grounding block attached to the DIN rail. The module is connected to ground through the DIN rail. A ground wire should be connected from the grounding block to the AC power ground. The wire should: A complete protection solution requires surge protection on the power and signal lines as shown in Figures 5 and 6. The input power to a power supply should be protected. −− be the same diameter/gauge as the power ground wire. Power Supply −− not be placed next to or near a signal wire. Output DC 24 V 5 A 13 14 DC OK Ι< ΙN - - – + - + + + Boost QUINT POWER DC OK PLC/Controller 18-29.5 V Input AC 100-240 V L Protected OUT N PE 2 4 6 PT 2PE/S 120AC-ST UC : 150 VAC IN : 2.5 kA 28 39 33 4 Unprotected IN 1 3 5 L N GND Figure 5. PT…X1-BE with common reference for Inputs 2 Phoenix Contact 2555A Power Supply Instrumentation and Control Surge Protection Output DC 24 V 5 A 13 14 DC OK Ι< ΙN - - – + - + + + Boost QUINT POWER DC OK L N Output Output Output Output Input AC 100-240 V Protected OUT PLC/Controller 18-29.5 V PE 2 4 6 PT 2PE/S 120AC-ST UC : 150 VAC IN : 2.5 kA 28 39 33 4 Unprotected IN 1 3 5 L N GND Figure 6. PT…X1-BE with common reference for Outputs Figures 5 and 6 display the complete surge protection solution with proper grounding and bonding. The power supply is protected from a surge using PLUGTRAB PT on the signal line from the field. Both units are bonded to the same ground, single point grounding, using low impedance DIN rail and grounding wire. 2555A Phoenix Contact 3 Instrumentation and Control Surge Protection IN 1 2 5 6 7 8 11 12 9 10 3 4 OUT 8 11 12 OUT IN 9 10 3 4 Figure 8. PT 2X1 circuit schematic Figure 7. PT 4X1 circuit schematic 2 7 Products Description of signal protection Type PLUGTRAB plug, 5 V DC PT 2X1-5DC-ST 2856061 PLUGTRAB plug, 12 V DC PT 2X1-12DC-ST 2856074 PLUGTRAB plug, 24 V DC PT 2X1-24DC-ST 2856087 PLUGTRAB plug, 12 V AC PT 2X1-12AC-ST 2856090 PLUGTRAB plug, 24 V AC PT 2X1-24AC-ST 2856100 PLUGTRAB base element, accepts PT 2X1 plugs PT 2X1-BE 2856139 PLUGTRAB base element, includes integrated gas discharge tube, accepts PT 2X1… plugs PT 2X1+F-BE 2856142 PLUGTRAB plug, 5 V DC PT 4X1-5DC-ST 2838306 PLUGTRAB plug, 12 V DC PT 4X1-12DC-ST 2838319 PLUGTRAB plug, 24 V DC PT 4X1-24DC-ST 2838322 PLUGTRAB plug, 48 V DC PT 4X1-48DC-ST 2858014 PLUGTRAB plug, 12 V AC PT 4X1-12AC-ST 2838348 PLUGTRAB plug, 24 V AC PT 4X1-24AC-ST 2838351 PLUGTRAB base element, accepts PT 4X1 plugs PT 4X1-BE 2839363 PLUGTRAB base element, includes integrated gas discharge tube, accepts PT 4X1… plugs PT 4X1+F-BE 2839376 Power protection Type MAINS-PLUGTRAB, 120 V AC PT 2-PE/S-120AC/FM 2856812 MAINS-PLUGTRAB, 230 V AC PT 2-PE/S-230AC/FM 2858357 MAINS-PLUGTRAB plug, 120 V AC PT 2PE-120AC-ST 2839334 MAINS -PLUGTRAB plug, 230 V AC PT 2PE-230AC-ST 2839347 3 Order No. Order No. Accessories Description Type Tester, for checking the functions of TRABTECH protective devices, includes adapter for PLUGTRAB devices CHECKMASTER 2838924 Test adapter, for PLUGTRAB CM-PA-PT/A 2816933 Shield, fast connection, 3-6 mm diameter SSA 3-6 2839295 Zach marker strip, 10-section, printed horizontally ZB 5 :UNBEDRUCKT 1050004 Zach marker strip, 10-section, printed horizontally ZB 18 :UNBEDRUCKT 2809128 2555A Phoenix Contact • P.O. Box 4100 • Harrisburg, PA 17111-0100 • USA Sales: 1-800-888-7388 • Technical Service: 1-800-888-7388 www.phoenixcontact.com Order No. 4