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21

3. Control Units

Intrinsic Safety

3

Intrinsically Safe

Mounting

R

Rack Mounted

L

Wall Mounted

Mains Voltage

1

220/240

Volts
2

110/120

Volts

Output Relay

S

Single Pole Changeover

D

Double Pole Changeover

M E P 3 L / 1 D

4. Racks

Intrinsic Safety

3

Intrinsically Safe

Number of spaces for control units

01 to 14
Remaining spaces are blanked off

M E P 3 B / 0 7

Содержание Mobrey

Страница 1: ...tallation 12 2 4 Wiring 12 Cables Head amplifier Control Unit 2 5 Intrinsically safe application 15 3 Fault Finding 16 4 Specification and description 4 1 Sensors 17 4 2 Head amplifiers 17 4 3 Control Units 18 5 Recommended Spare Parts Appendices Appendix I Part Numbers 20 Appendix II List of illustrations 22 Appendix III List of tables 22 Maintenance Inspection 23 For instructions specific to uni...

Страница 2: ... fitted as close as practical to and not be obstructed by the equipment It must be double pole and marked as the disconnection device Each relay circuit must be protected by a fuse not exceeding the maximum rated current for the relay as specified in the manual On wall mount unit disconnect supply before removing control unit from base Control units must be correctly assembled to achive stated IP ...

Страница 3: ... b Hi Sens cylindrical sensors Figure 1 1 Gap sensor cut away to show construction The Hi Sens sensor consists of two ultrasonic transducers mounted on the inside of a cylinder When the sensor is not submersed in the liquid the signal from one transducer resonates round the cylinder like a bell ringing If the liquid rises up around the sensor this ringing is damped and the signal received by the s...

Страница 4: ...the attenuation s are similar and the attenuation method does not work then the reflection method must be used If an ultrasonic beam is transmitted from one liquid to another at a suitable angle it does not go straight through the interface but is bent so that it does not reach the receiver crystal If there is no interface in the gap but only one liquid then the beam travels in a straight line is ...

Страница 5: ...ol room can be 1km or more There are five versions available which fall into two categories i Normal acting head amplifiers When the sensor is in its normal state i e Dry for Hi Sens and Wet for Gap Sensors the signal from the transmitting transducer is received by the second transducer and fed back to the head amplifier causing it to transmit current pulses to the control unit If an alarm state o...

Страница 6: ...nt mounted head amplifiers where the coaxial cable linking head amplifier and sensor may be exposed on site This is only operable where the sensor in use has Earth continuity between the two coaxial cables see section 2 2 Lack of screen continuity along these cables causes the head amplifier to signal a fault condition to the control room readout unit To use the facility a wire link in the head am...

Страница 7: ...d be off The lid of the head amplifier unit is removed by undoing the four screws or Allen bolts Care should be taken not to damage the sealing gasket which should be replaced with the lid When using integral head amplifiers the sensor must not be unscrewed from the head amplifier unit as this is likely to damage the internal wiring and may violate ATEX approval The marine head amplifier S PM has ...

Страница 8: ... fitted 4 Gradually increase the gain until the control unit indicates normal or alarm for inverse acting head amplifiers Note the position of the potentiometer and gain switch This is the lower end of the working range 5 Remove the sensor from the liquid and allow the liquid to drain away Ensure that nothing is touching the sensor body The control unit should now indicate alarm or normal for inve...

Страница 9: ...d if spurious alarms cannot be overcome by increasing the delay The gain should be decreased if the unit fails to detect interfaces 5 For the reflection method the sensor should be mounted at an angle of 10º to the horizontal 6 Where the interface consists of an emulsion layer the sensor functions as the reflection method giving an Alarm condition only at the interface but in this case it is not n...

Страница 10: ...anged sensors arrange a suitable counter flange and fit using a gasket tightening the bolts evenly If possible the bridge of sensors 302S and 402S should be to the side of the gap and not above or below it and all gap sensors should have their gaps vertical This is so that any sludge in the tank cannot settle on the faces of the sensor Interface probes 402S and 433S may be mounted at an angle of 1...

Страница 11: ...11 DIN RAIL Mounting Clip available on request Figure 2 3 Control unit mounting details ...

Страница 12: ...k If desirable the connectors and modules can be repositioned in the rack To assist with cable wiring the connector block wire access faces the rear of the rack and the screw terminals are therefore angled To fit cable to the 5 modules closest to the right hand end of the rack numbers 10 14 it is necessary to release the connector and rotate it slightly to allow screwdriver access 2 4 Wiring i Cab...

Страница 13: ...s Figure 2 6 shows the terminal arrangements The head amplifier cable cores are connected to the and terminals on the control unit ensuring that A and D is connected to the terminal and B or C respectively is connected to the terminal The screen is connected to the SCN terminal marked sensor on the rack mounted unit The main connections are made to the L and N terminals of the control unit The con...

Страница 14: ...14 Figure 2 6 Control Unit Connections MEP 3L I S Relays Screen to be connected To head amplifier MEP 3B I S Protective Earth Neutral Live Supply ...

Страница 15: ... be earthed using at least 4mm2 wire All screen earth and main earth connections must be commoned In the case of the rack unit MEP3B the chassis must be earthed and each unit connected independently to the chassis earth iv I S cables must exit the control separately from the mains and relay cables v It is the responsibility of the installer to ensure that local codes of practice are followed Intri...

Страница 16: ...ding unit 120V K1796 T 125mA 35A Breaking capacity All fuses are 5mm x 20mm IEC 127 Fault indicated i Check for short circuits between the head amplifier cable cores or open circuits Disconnect the cable from the control unit and measure the resistance between the two wires to the head amplifier The resistance should be a little over 100K ohm in one direction and about 3 5K ohms to 50k ohms in the...

Страница 17: ... unit 1 or 3 7 MHz Potentiometer adjustable switchable ranges on MEP I Current pulses transmitted to control unit in Normal mode 270 Hz 25 to 85ºC Optional MEP AI S PI S PM simulates a break in the sensor cables fault test MEP XI simulates active sensor stopping pulses alarm test i S PI IP54 Aluminium housing mounted on sensor Pg 16 cable entries ii S PM IP68 Gunmetal or Stainless steel mounted on...

Страница 18: ...EP L and MEP R are intrinsically safe See table 2 2 for certificate details Approximately 11 5V 20mA maximum 10ºC to 65ºC The units must be left to warm up for 15 minutes before being exposed to sub zero temperatures Maximum altitude 2000m Maximum humidity 95 CAT II 264V a c MAX Pollution 2 CAT III 132V a c MAX Pollution 2 3 LEDs Green Normal Red Alarm Amber Fault At least one LED should be on at ...

Страница 19: ...2 Control Units i Fuses Standard Control Unit MEP L 1 220 240V K179 T 63mA 35A Breaking capacity IEC 127 MEP L 2 110 120V K1796 T 125mA 35A Breaking capacity IEC 127 Rack Mounted Unit MEP R All voltages H1525 F 500mA 1500A Breaking capacity IEC127 All fuses are 5mm 20mm ii Edge Connectors Rack units only I S units K1806 4 way edge connector MEP3R K1805 12 way edge connector Screws for mounting con...

Страница 20: ... C Sensor Connection 0 PVC Cable Phono Plugs 1 PTFE Cable Phono Plugs 4 PVC Cable BNC Plugs 5 PTFE Cable BNC Plugs 7 PVC Cable Pins 8 PTFE Cable Pins 9 Special Cable M Marine Head Amplifier I Industrial Head Amplifier J Junction Box 3 0 2 S D P 8 0 T Note Pre 1984 sensors have an M or an I in the third place to indicate Marine or Industrial head amplifier 2 Head Amplifiers Adjacent mounted Intrins...

Страница 21: ...ted L Wall Mounted Mains Voltage 1 220 240 Volts 2 110 120 Volts Output Relay S Single Pole Changeover D Double Pole Changeover M E P 3 L 1 D 4 Racks Intrinsic Safety 3 Intrinsically Safe Number of spaces for control units 01 to 14 Remaining spaces are blanked off M E P 3 B 0 7 ...

Страница 22: ...Amplifier 7 2 2 Adjacent head amplifier 8 2 3 Control unit mounting details 11 2 4 Wiring Summary 12 2 5 Sensor connections to adjacent head amplifier 13 2 6 Control unit connections 14 Appendix III List of tables Section Table Title Page 1 Introduction 1 1 Head amplifier types 6 1 2 Head amplifier operation 6 2 Installation 2 1 Relay ratings and fuses 13 2 2 Approvals 15 4 Specification 4 1 Senso...

Страница 23: ...o periodic inspection by a qualified person to ensure that the installation including wiring and equipment housing is safe Clean only with a damp cloth ensuring that no moisture enters control unit Check unit for damage and if damaged do not use ...

Страница 24: ...merson Electric Co Rosemount is a registered trademark of Rosemount Inc Mobrey is a registered trademark of Mobrey Ltd All other marks are the property of their respective owners We reserve the right to modify or improve the designs or specifications of product and services at any time without notice Americas Emerson Process Management Rosemount Inc 8200 Market Boulevard Chanhassen MN USA 55317 T ...

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