Instruction/ maintenance manual of the product TAN-1005 Western Telematic
Go to page of 8
T elematic A member of The MTL Instruments Group plc Surge Suppr ession for Zone 0 Locations Synopsis This note discusses the surge pr otection requirements of intrinsically safe circuits entering a Zone 0 hazardous area. It analyses the potential gradients generated by lightning strikes and their possible r outes of invasion.
CONTENTS PAGE 1 INTRODUCTION ........................................................................................................................... 1 2 INTRINSIC SAFETY REQUIREMENTS FOR EARTHING AND BONDING .......................................
SURGE SUPPRESSION FOR ZONE 0 LOCA TIONS tal requirement of all the methods of protection used for power equip- ment. It is not usual for lightning induced current to directly cause enough heating to create a hazard by temperature ignition, since the current pulses are too short to create a sustained high temperature.
tion from this possibility or sited with care in the shelter of some other protrusion. The diagram shows a two wire 4 to 20 milliamp transmitter with internal isolation fed from a galvanic isolator . T o establish the order of the problem some assumptions are made which cannot be fully justified but are believed to be reasonable.
4 PROTECTION OF THE SENSOR AND TRANSMITTER The problem of surge protection of the transmitter and sensor is rela- tively easy to solve since it is only necessar y to prevent significant voltage differences so as to avoid ignition capable sparks.
The system should be designed so that when the surge current is di- ver ted the voltage drop across the bonding conductor does not create a large voltage across the isolator . Figure 4 gives an illustration of a satisfactor y system. With the currents and distances indicated the iso- lator is still subjected to a 1.
supply will contain a significant amount of surges but if for any reason the supply is particularly exposed to invasion from lightning induced surges then some consideration to suppressing the main supply should be given. A practical economic solution is to protect the supply input to the com- puter system as indicated in figure 5.
1) Simple apparatus shall not achieve safety by the inclusion of voltage and/or current limiting and/or suppression devices. 2) Simple apparatus shall not contain any means of increasing the available voltage or current, e.g. circuits for the genera- tion of ancillar y power supplies.
An important point after buying a device Western Telematic TAN-1005 (or even before the purchase) is to read its user manual. We should do this for several simple reasons:
If you have not bought Western Telematic TAN-1005 yet, this is a good time to familiarize yourself with the basic data on the product. First of all view first pages of the manual, you can find above. You should find there the most important technical data Western Telematic TAN-1005 - thus you can check whether the hardware meets your expectations. When delving into next pages of the user manual, Western Telematic TAN-1005 you will learn all the available features of the product, as well as information on its operation. The information that you get Western Telematic TAN-1005 will certainly help you make a decision on the purchase.
If you already are a holder of Western Telematic TAN-1005, but have not read the manual yet, you should do it for the reasons described above. You will learn then if you properly used the available features, and whether you have not made any mistakes, which can shorten the lifetime Western Telematic TAN-1005.
However, one of the most important roles played by the user manual is to help in solving problems with Western Telematic TAN-1005. Almost always you will find there Troubleshooting, which are the most frequently occurring failures and malfunctions of the device Western Telematic TAN-1005 along with tips on how to solve them. Even if you fail to solve the problem, the manual will show you a further procedure – contact to the customer service center or the nearest service center
