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Instruction Manual

INM7700

MTL7700 Series
Shunt-diode safety barriers

Содержание MTL7700 Series

Страница 1: ...Instruction Manual INM7700 MTL7700 Series Shunt diode safety barriers ...

Страница 2: ...ii INM7700 6 Jan 2010 ...

Страница 3: ...ons 7 5 3 Connections to plant earth 7 5 4 Connections to dummy barriers 9 6 MAINTENANCE 9 6 1 General 9 6 2 Routine inspection 9 7 FAULT FINDING 10 7 1 Introduction 10 7 2 Power supply check 11 7 3 Barrier resistance test 11 8 EQUIPMENT AND BARRIER TESTS 11 8 1 Thermocouple and RTD tests 11 8 2 Barrier tests 11 8 3 Tests for Active Barriers 12 8 4 Test tables for passive barriers 14 APPENDIX A TY...

Страница 4: ...INM7700 6 Jan 2010 iv ...

Страница 5: ...ith the product these publications are available either from the company website www mtl inst com or on request from your local MTL office 2 DESCRIPTION 2 1 Introduction MTL7700 Series fourth generation intrinsically safe shunt diode safety barriers are innovative successors to the MTL700 Series MTL7700 Series barriers are 1 2 or 3 channel devices that use intrinsically safe explosion protection t...

Страница 6: ...for mounting over a column of barriers for marking barrier locations Supplied with labels in 1m lengths for cutting to size TGL7700 Spare labels for use with TAG57 tagging strips 0 5m strips supplied in sets of 10 IMB57 Tagging strip supports Two needed for each tagging strip It can also be used as centre support by breaking off the top end tab Power accessories figure 3 BPL7700 Power link for fee...

Страница 7: ...ing accessories As a guide on a given length of DIN rail allow space length for a Barrier packing pitch 12 6mm b ETL7000 earth terminals 10mm each minimum of two c IMB57 tagging strip support 16 0mm minimum of if specified two d ISP7000 insulating spacer 14 7mm minimum of if specified two e ERB57S or O earth rail 8 mm minimum of two mounting bracket if specified See Note in section 4 3 2 Make sure...

Страница 8: ...f applicable and complies with the recommendations contained in the relevant sections of IEC 60079 14 for the gas group temperature classification and area classification required 2 4 1 6 2 Make sure the barriers are of the correct type and polarity as specified in the safety documentation 3 4 1 Make sure all barriers are mounted the right way round and are properly attached so that the essential ...

Страница 9: ...inals are recommended one at either end of a column of barriers to provide redundancy and to simplify earth testing procedures WARNING Apart from rare occasions when the mounting surface carries the IS earth the ONLY method of providing the IS earth connection from any one column of MTL7700 Series barriers is from ETL7000 earth terminals Never make the plant IS earth connection to the earth screen...

Страница 10: ...blies IMB57 The tagging strip assembly figure 12 identifies the location of individual barriers ensuring that they are replaced correctly after removal for maintenance or testing Once installed the tagging strip pivots upwards to provide access to and allow removal of individual barriers Each assembly uses two tagging strip supports IMB57 a tagging strip TAG57 and tag labels TGL7700 The assembly i...

Страница 11: ...A for specific connections for individual barriers and applications 5 2 3 Bussed Power applications and connections When a number of barriers use a common power supply the optional power link BPL7700 can be used Typical applications include hazardous area switches solenoids and 4 20mA transmitters and the barriers it can be used with are the MTL7706 MTL7707 MTL7787 MTL7787P and MTL774x See figure ...

Страница 12: ... see section 4 3 4 an earth conductor normally copper wire with a cross sectional area of at least 4mm2 12AWG must be connected between ETM7 earth terminals located at each end of the rail and the spare terminals on the ETL7000 terminals at each end of the column of barriers See figure 17 5 3 4 Hazardous area equipment isolation Hazardous area equipment and interconnections should be isolated from...

Страница 13: ...ly to the neutral star point This reduces interference problems but is not essential for safety reasons f In general the use of barriers in all measurement leads reduces the possibility of earth circulating currents causing measurement problems g Resistance from the neutral star point to terrestrial earth via the buried earth mat or rods is determined by other regulations and is not modified or de...

Страница 14: ...e and their operation is easy to check However when fault finding is necessary it must only be undertaken after checking with plant personnel responsible for safety that it is safe to proceed The fault finding procedures described in this section call for the use of a digital multimeter this being the most common type used However other types can be used provided their characteristics when measuri...

Страница 15: ...mocouple circuits can be protected by using an MTL7760ac barrier as shown in figure 21 This permits the thermocouple output to be measured without needing special authorisation to use uncertified thermocouple test equipment As it is seldom possible to measure accurately the temperatures of thermocouples located in hazardous areas a safe way of adjusting calibration tables to compensate for plant t...

Страница 16: ...ers 8 3 1 Tests for the MTL7706 Comprehensive testing requires specialised equipment beyond the scope of on site tests However an effective test which will confirm that the unit is operating correctly is shown in figure 24 Ammeter 1 measures the transmitter simulator current of between 4 and 20mA flowing from terminal 4 and the safe area load current flowing to terminal 4 simultaneously Since thes...

Страница 17: ...th an ohmeter check the status of the output contacts according to Table 3 3 4 1 2 MTL7742 5 6 7 8 Bussed Power 24V Vs Vs 2KΩ Figure 27 Test circuit for MTL7742 3 4 1 2 MTL7745 5 6 620W 10kW 24V Bussed Power Line Fault Output Vs Vs Figure 30 Test circuit for MTL7745 Table 3 Test conditions for MTL7745 3 4 1 2 MTL7743 5 6 7 8 Bussed Power 24V Vs Vs Channel 1 Channel 2 Channel 1 Channel 2 Figure 28 ...

Страница 18: ...ode and 0 3V for each Schottky diode the expected reading across the diode chain can be determined BARRIER DATA MULTIMETER TESTS CONSTANT CURRENT TESTS MTL Safety End to end Diode Diode Terminal Terminal model Description Resistance Test Test Voltage Voltage No Ω Ω ve ve 10μ μA 20mA V Ω Ω mA Min Max Min Max Min Max 7758 7 5 10 750 14 17 Vfz x 1 6 6 9 6 6 7 7758 7 5 10 750 14 17 Vfz x 1 6 6 9 6 6 7...

Страница 19: ...157 84 92 9 6 10 9 10 4 11 2 Table 7 Dual channel ac barriers BARRIER DATA MULTIMETER TESTS CONSTANT CURRENT TESTS MTL Safety End to end Diode Diode Terminal Terminal model Description Resistance Test Test Voltage Voltage No Ω Ω ve ve 10μ μA 20mA V Ω Ω mA Min Max Min Max Min Max 7760ac 10 50 200 62 75 6 9 5 6 9 9 8 7765ac 15 100 150 112 124 12 14 1 12 7 14 4 7778ac 28 600 47 614 651 24 0 24 4 25 4...

Страница 20: ...Min Max Min Max 7787 28 300 93 311 333 Vfz x 2 26 6 27 4 26 7 27 6 7787 ch2 28 0 9V 26 Vfz x 2 26 6 27 4 26 7 27 6 7787P 28 237 119 241 253 Vfz x 3 26 4 27 4 26 5 27 6 7787P ch2 28 0 9V 26 Vfz x 2 26 6 27 4 26 7 27 6 7789 38 300 93 614 651 Vfz x 2 26 6 27 4 26 7 27 6 7789 ch2 28 0 9V 26 Vfz x 2 26 6 27 4 26 7 27 6 Table 10 Diode return barriers Note Vfz is the voltage dropped by a forward biased z...

Страница 21: ...c Receiver 7 5 3 4 1 2 MTL7755ac Receiver Figure A6 Low level analogue inputs RTD s Figure A2 2 wire transmitters with 250Ω conditioning Hazardous Area Safe Area 3 4 1 2 MTL7760ac MTL7765ac MTL7778ac Recorder Controller Data logger Computer Compensating cable Figure A3 Thermocouple mV input Hazardous Area Safe Area 3 4 1 2 MTL7743 MTL7744 7 8 5 6 Logic signal Logic signal Power Figure A7 2 channel...

Страница 22: ... bridges Hazardous Area Safe Area 3 4 1 2 MTL7745 5 6 620Ω 10kΩ 22 9 30V LFD COM CH 1 Power Bus Figure A10 Single channel switch proximity input with Line Fault Detect Hazardous Area Safe Area 3 4 1 2 MTL7789 7 8 5 6 Power 26V Power 26V Power Bus Figure A11 Low power digital outputs Hazardous Area Safe Area 3 4 1 2 MTL7741 5 6 7 8 NO COM Power Bus 22 9V 30V NC Figure A12 Single channel switch prox...

Страница 23: ......

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