background image

13

INM7700-6   

Jan 2010

Input

Output Line Fault

Open circuit

Open

Closed

Short circuit

Closed

Closed

620

Ω

Closed

Open

10K

Ω

Open

Open

8.3.3.2

Testing MTL7742 Barriers

The MTL7742 is a single channel switch/prox input barrier with an
open collector solid state interface to the safe area equipment. To
verify correct operation proceed as follows:

a) Connect the barrier as shown in figure 27.
b) Check that the LED is on when the input switch is closed, and off

when the input switch is open.

8.3.3.3

Testing MTL7743 Barriers

The MTL7743 is a dual channel switch/prox input barrier, each
channel with a relay interface to the safe area equipment. To verify
correct operation proceed as follows:

a) Connect the barrier as shown in figure 28.
b) With an ohmeter, check that the output contacts (terminal 1 & 2)

close when the input switch for channel 1 is closed.

c) Repeat the procedure for channel 2.

8.3.3.4

Testing MTL7744 Barriers

A dual channel version of the MTL7742, this module provides two
solid state interfaces for prox/switch inputs. To verify correct
operation proceed as follows:

a) Connect the barrier as shown in figure 29.
b) Connect power via the power bus
c) Check that the LED is on when the input switch is closed for

channel 1, and off when the input switch is open for channel 1.

d) Repeat the procedure for channel 2.

8.3.3.5

Testing MTL7745 Barriers

This module is a single channel interface for prox/switch inputs with
line fault detection. To verify correct operation proceed as follows:

a) Connect the barrier as shown in figure 30.
b) With 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-

}

2K

Ω

Figure 27:

Test circuit for MTL7742

3
4

1
2

MTL7745

5
6

620

W

10k

W

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:

Test circuit for MTL7743

3
4

1
2

MTL7744

5
6

7
8

Bussed Power

24V

Vs+

Vs-

2K

W

2K

W

Channel 1

Channel 2

Channel

1

Channel

2

Figure 29:

Test circuit for MTL7744

8.3.3

Tests for MTL774x 

The MTL774x range are switch/prox input barriers with a choice of
changeover relay contacts or a solid state switch acting as the safe
area interface. Relay contacts provide a universal interface capable
of switching a wide range of signals including ac, low level and high
level voltages. Phase reversal is achieved by connecting the normally
open or normally closed contacts as required. The solid state switch
variants can be configured to switch from a power rail or down to
ground and makes these barriers ideal for high switching frequency
applications.

When testing bus powered barriers use either an MTL7798 Power
Feed module or an MTL7799 dummy barrier for direct ‘feed-through’
connection of a 24V dc supply.

8.3.3.1

Testing MTL7741 Barriers

The MTL7741 is a single channel switch/prox input barrier with
changeover relay contacts acting as the safe area interface. To verify
correct operation proceed as follows:

a) Connect the barrier as shown in figure 26.
b) With an ohmeter, check that the output contacts (terminal 5 & 6)

close when the input switch is closed.

3
4

1
2

MTL7741

5
6

7
8

Bussed Power

24V

Vs+

Vs–

Output

Figure 26:

Test circuit for MTL7741

www.calcert.com

[email protected]

1.888.610.7664

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Summary of Contents for MTL770 Series

Page 1: ...Instruction Manual INM7700 MTL7700 Series Shunt diode safety barriers www calcert com sales calcert com 1 888 610 7664 0 5 10 15 20 25 30...

Page 2: ...ii INM7700 6 Jan 2010 www calcert com sales calcert com 1 888 610 7664 0 5 10 15 20 25 30...

Page 3: ...h 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 EQUIPME...

Page 4: ...INM7700 6 Jan 2010 iv www calcert com sales calcert com 1 888 610 7664 0 5 10 15 20 25 30...

Page 5: ...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 s...

Page 6: ...ers 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 s...

Page 7: ...en 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 ISP700...

Page 8: ...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 typ...

Page 9: ...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 providin...

Page 10: ...bly 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 provi...

Page 11: ...vidual 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 in...

Page 12: ...or 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 termina...

Page 13: ...educes 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...

Page 14: ...ck 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 th...

Page 15: ...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 se...

Page 16: ...rehensive 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 mea...

Page 17: ...he output contacts according to Table 3 3 4 1 2 MTL7742 5 6 7 8 Bussed Power 24V Vs Vs 2K Figure 27 Test circuit for MTL7742 3 4 1 2 MTL7745 5 6 620W 10kW 24V Bussed Power Line Fault Output Vs Vs Figu...

Page 18: ...e 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 Te...

Page 19: ...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 ve ve 10 A...

Page 20: ...fz 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...

Page 21: ...ceiver Figure A6 Low level analogue inputs RTD s Figure A2 2 wire transmitters with 250 conditioning Hazardous Area Safe Area 3 4 1 2 MTL7760ac MTL7765ac MTL7778ac Recorder Controller Data logger Comp...

Page 22: ...3 4 1 2 MTL7745 5 6 620 10k 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...

Page 23: ...www calcert com sales calcert com 1 888 610 7664 0 5 10 15 20 25 30...

Page 24: ...91 0 44 24501660 24501857 Fax 91 0 44 24501463 E mail sales mtlindia com MTL Italia srl Via Cant 11 I 20092 Cinisello Balsamo MI Italy Tel 39 0 2 61802011 Fax 39 0 2 61294560 E mail info mtl inst it M...

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