Datasheet TBU-RS (Bourns) - 3

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TBU-RSxxx-300-WH Series - TBU® High-Speed Protector Device Operation (Continued) Protection Against Lightning Surges
To protect against surge levels of 500 V and above (see table below), the TBU-RSxxx-300 will require an external OVP device, also referred to here as “Primary Protector”. The table below outlines how the primary protector, GDT or Thyristor, when used with the TBU-RSxxx-300 device will afford protection of the RS-485 interface device to lightning waveform surges up to 4 kV.
Primary Protectors for TBU-RSxxx-300-WH Series - Passing Combinations Standard IEC 61000-4-5 Generator Impedance Class 0 1 2 3 4 Peak Test Voltage 25 V 500 V 1 kV 2 kV 4 kV
TBU-RS055-300-WH TBU-RS055-300-WH TBU-RS055-300-WH TBU-RS055-300-WH TBU-RS085-300-WH Req. = 42 Ω Primary Protector None None TISP4350H3BJR-S TISP4350H3BJR-S TISP4350J3BJR-S TBU-RS055-300-WH TBU-RS055-300-WH TBU-RS055-300-WH TBU-RS055-300-WH TBU-RS085-300-WH Req. = 12 Ω Primary Protector None TISP4350H3BJR-S TISP4350H3BJR-S TISP4350H3BJR-S TISP4350J3BJR-S TBU-RS055-300-WH TBU-RS055-300-WH TBU-RS055-300-WH TBU-RS085-300-WH TBU-RS085-300-WH Req. = 2 Ω Primary Protector None TISP4350H3BJR-S TISP4350H3BJR-S GDT-2054-23-SM GDT-2054-23-SM When selecting the Integrated RS-485 interface protector and primary protection components, it is important to be aware of the maximum surge current available. The TISP4350H3BJR can endure 300 A peak and the TISP4350J3BJR can endure 800 A in an 8/20 µs surge. A 1 kV surge can provide 500 A into a 2 ohm load, so the 800 A TISP® device is required. At 4 kV, high voltage and current combine to require the 800 A TISP® device and the 850 V Model TBU-RS085-300. If low impedance exposure to lightning surges is anticipated, the GDT with the 850 V Model TBU-RS085-300 provides the best combination. The GDT takes the current and the 850 V TBU-RS device withstands the GDT let-through voltage. Specifications are subject to change without notice. Users should verify actual device performance in their specific applications. The products described herein and this document are subject to specific legal disclaimers as set forth on the last page of this document, and at www.bourns.com/docs/legal/disclaimer.pdf.