Small Scale PA. Presented by: James Powell, P.Eng. Restricted Siemens AG 20XX All rights reserved.

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Camilla Reed
5 years ago
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1 Small Scale PA Presented by: James Powell, P.Eng. siemens.com/answers

2 Agenda What has changed? The application The HART solution The problem with HART/ why PA The PA solutions How do the economics work out? Page 2

3 What has changed? Up until the last few years, the cheapest Profibus master was still over a thousand. Then -HMS Ethernet to Profibus gateway (~450 ) -S micro PLC with Profibus interface (~500 ) -IFAK gateways (~1200 ) Plus, to link to PA, last year there were two manufacturers, now there are 4: -Siemens -P+F -Procentec -IFAK Profibus is not just for large applications anymore! Page 3

4 Application: Small Scale Oil and Gas Page 4

5 The HART solution Multi-drop HART Used a HART to Modbus RTU converter (HCS by Moore Industries) Results 90% of sites worked with the odd problem 9% of sites were problematic 1% of sites did not work at all 200 ohms 5.76 V V 3.6 ma I total = 8*3.6 = 28.8 ma 28V Minimum Voltage for LR250 ~ 18.2 V Page 5

6 Problem with HART -Sizing the HART resister (having to modify it in cold weather operation) -HART waveform 200 ohms 5.76 V V 3.6 ma I total = 8*3.6 = 28.8 ma 28V Page 6 Minimum Voltage for LR250 ~ 18.2 V

7 Why Profibus PA? Very robust physical layer Easier to put together than multi-drop HART (no HART resister to size) New features possible: - IS wiring possible - status information - transparency to the instrument Page 7

8 Robust Physical Layer - Examples Jetso-Diesel Univar Orange Sky Baker Petrolite Page 8

9 Simple Wiring Simple Trunk wiring No fancy junction boxes Simple terminal strips No HART resister Page 9

10 Flame-proof vs. Intrinsically Safe Costs $$ EX Proof Rigid Conduit Epoxy Seals Expensive fittings Longer time to install Not very flexible More expensive Can t do live service Not as safe Intrinsically Safe Flexible cable Plastic cable glands Simple to install Safer (less prone to human error) Live servicing Page 10

11 Status Information is transmitted each time IEEE FLOATING POINT VALUE STATUS BYTE BYTE 1 BYTE 2 BYTE 3 BYTE 4 STATUS Page 11

12 Transparency* to the Instrument is now possible with new hardware! *Note: Transparency can be done with HART as well, but not with the hardware they were using Page 12

13 1 st Trial Site! Picked the site that HART would not work at all Replaced the LR250 HART heads with LR250 PA heads Changed the wiring Used simple terminal strips It worked right away! No repeats and a perfect waveform! Page 13

Gateway (Profibus master on One side and Modbus TCP/IP server on the Other side)

14 The current solution! GSM/GPRS Modem Ethernet Switch Micro-PLC (Schneider Electric) SITRANS LR250 Anybus Gateway (Profibus master on One side and Modbus TCP/IP server on the Other side) Siemens DP/PA Ex Couplers Pactware with SITRANS DTM PROFIBUS Pa (31.25 K bit/s) PROFIBUS Pa (31.25 K bit/s) MODBUS TCP/IP INDUSTRIAL ETHERNET Page 14 CLASS 1 DIV 1

15 The current solution! Page 15

16 Economics of PA and IS instead of Ex construction Multi-drop HART (using Ex) -Used cheaper gateway -Had no transparency -Expensive Ex fittings -Because of Ex fittings, instruments are hard to remove - HART comms did not always work Profibus PA (using IS) -Used cheaper fittings -Did not have be careful with conduit -Had a more expensive gateway -Required couplers -Instruments were slightly more expensive -Had transparency -Worked! For their typical application, the Profibus solution was only between 15% and 20% more expensive then HART multi-drop, but cheaper when you take into account that: - Profibus worked! - Transparency could reduce site visits - if you have to change an instruments, it was now easy! Page 16

17 Alternate Solution GSM/GPRS Modem Micro-PLC Ethernet Switch IFAK IsNet Lite with Modbus and PA module Pactware with SITRANS DTM LR250 PROFIBUS Pa (31.25 K bit/s) This has a lower capital costs PROFIBUS Pa (31.25 K bit/s) Profinet Page 17 CLASS 1 DIV 1

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19 Contact James Powell Business Developer Process Instruments / Siemens Canada 1954 Technology Dr. Peterborough, Ontario, Canada, K9J7B1 Phone: +49 (123) Fax: +49 (123) Mobile: +49 (123) james.powell@siemens.com siemens.com/answers Page 19

Profibus and Modbus: a comparison

James Powell, P. Eng. Profibus and Modbus: a comparison We live in a multi-protocol world and this will likely not change anytime soon. Different protocols work better in different applications. I have