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Siemens QGO21 Series, Basic Documentation

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Siemens QGO21 Series Basic Documentation Download Page 16

16/27 

Building Technologies Division 

Oxygen Sensor QGO21... 

CC1P7845en 

 

5 Description of functions 

06.12.2017 

 

that is =          = 21.5        or

         = 20.9 mV at T = 700 °C = 973 K

R

4 x F

V

K

R x T

4 x F

 

 

 

Figure 3: Nernst voltage as a function of the oxygen concentration at a cell temperature of 700 °C 

 

Summary of Contents for QGO21 Series

Page 1: ...and this Basic Documentation are intended for use by OEMs which integrate the oxygen sensor in their products Note The QGO21 may only be operated with the following system components Type AZL52 LMV52 2 LMV52 4 PLL52 from software version 04 90 05 00 10 10 01 50 QGO21 must be selected as the O2 sensor in the O2 module ...

Page 2: ...ilding Technologies Division Oxygen Sensor QGO21 CC1P7845en Weishaupt 06 12 2017 Supplementary documentation Basic Documentation LMV5 P7550 User Manual LMV52 A7552 Mounting Instruction QGO21 M7845 4 319 0866 0 ...

Page 3: ...7 Service notes 10 1 8 Disposal notes 11 2 Overview 12 3 Assortment connections 13 4 Technical data 14 5 Description of functions 15 5 1 Functioning principle of the measuring cell 15 5 2 Impact of the cell s temperature 17 5 3 Impact of the reference gas 18 5 4 Switching on and switching off 18 5 5 Aging 18 6 Mechanical design of the sensor 19 7 Mounting and connecting the sensor 20 7 1 Mounting ...

Page 4: ...enance timer of LMV52 must be used to ensure that the maintenance interval is complied with see LMV52 User Documentation A7552 All setting instructions of the LMV52 must be observed see User Documentation A7552 chapter O2 control In particular we wish to draw your attention to the manipulated variable limitation that is described there The environment must be free from chemicals such as vapors fro...

Page 5: ...lse measurements which can lead to dangerous conditions Ensure that the hot QGO21 does not get into contact with explosive or inflammable gases QGO21 may only be used in conjunction with AGO21 Caution risk of burns There is a risk of burning since the measuring cell works at an operating temperature of 700 C and other accessible parts can get very hot too 60 C To prevent injury caused by the hot s...

Page 6: ...e time 1 3 Installation and mounting notes Ensure that the relevant national safety regulations are complied with The flue gas flow passing the measuring point should be homogeneous When mounted too close to air dampers or pipe bends faulty measurements can occur The exchange of fresh air in the connection area of the sensor with the reference air slots must be ensured and may never be covered up ...

Page 7: ...017 1 4 Electrical connection It is important to achieve practically disturbance and loss free signal transmission Never run the sensor cable together with other cables use a separate cable Observe the permissible length of the sensor cables and the relevant specification see Technical data ...

Page 8: ...m the heating up times must therefore be observed It is also recommended to keep the sensor activated during short burner off periods 2 days Prior to commissioning make the following mounting final checks Check to ensure that the sensor is correctly fitted to the mounting flange Ensure that the signal and power supply lines are correctly connected Electronic circuit Activate the electronic circuit...

Page 9: ...sured value distortion The O2 setpoint curve must not be set New QGO21 devices must be pre heated for up to 12 hours longer before no temporary O2 measured value distortion occurs and a relevant O2 value is achieved in the pre ventilation phase Older QGO21 devices must be replaced or cleaned if the relevant O2 value is not achieved in the pre ventilation phase within the specified time frame Note ...

Page 10: ...he level of contamination observed The recommended value for the first maintenance timer setting is 3 months The final value can then be set at a later stage based on the level of contamination observed The following maintenance work must be carried out if contamination is identified A cooling time of at least 2 hours must be observed Clean the sintered filter using a brass wire brush or compresse...

Page 11: ...Sensor QGO21 CC1P7845en 1 Safety notes 06 12 2017 1 8 Disposal notes The oxygen sensor contains electrical and electronic components and must not be disposed of together with household waste Local and currently valid legislation must be observed ...

Page 12: ...t point When used in connection with burner controls type LMV52 for residual oxygen control the efficiency of combustion will be improved and oxygen emissions minimized Supply air temperature sensor Flue gas temperature sensor O2 module PLL52 QGO21 CAN LMV52 Figure 1 Example General overview QGO21 consists of a stainless steel sensor tube with mounting flange retaining ring screwed on the front wi...

Page 13: ...7 AC 120 V BPZ QGO21 000D17 QGO21 000D17 Control unit for measurement of the rest of oxygen LMV52 with PLL52 See Basic Documentation P7550 Mounting flange for QGO21 BPZ AGO21 000A AGO21 000A Flange gasket for service BPZ 576920210 576920210 Sinter filter for service BPZ AGO742870012 AGO742870012 To be fixed to the QGO21 with screws with a width over flats of SW41 Single packing See Mounting instru...

Page 14: ...H Heavy oil to DIN 51603 3 and DIN 51603 5 Measuring range 0 2 20 9 O2 Perm cable length between QGO21 and PLL52 Max 10 m Supply lines mains cable Wire dia min 1 mm e g NYM3 x 1 5 Required operating temperature of measuring cell 700 C 50 C Tightening torque for sintered filters Min 6 Nm Max 7 Nm Measuring time Approx 12 min Storage DIN EN 60721 3 1 Climatic conditions Class 1K3 Mechanical conditio...

Page 15: ...of oxygen ions carries electrical charges that generate an electrical field across the platinum electrodes When in equilibrium the diffusion force compensates the force of the electrical field On the one hand the porous platinum electrodes serve for the catalytic conversion of the molecules into ions and vice versa O2 20 2e on the other for the acquisition of voltage The voltage across the electro...

Page 16: ...ion Oxygen Sensor QGO21 CC1P7845en 5 Description of functions 06 12 2017 that is 21 5 or 20 9 mV at T 700 C 973 K R 4 x F V K R x T 4 x F Figure 3 Nernst voltage as a function of the oxygen concentration at a cell temperature of 700 C ...

Page 17: ...xygen concentration The higher the temperature the higher the Nernst voltage and the lower the displayed oxygen concentration Figure 4 Impact of the cell s temperature on the oxygen value To limit the error the temperature in the PLL52 is also considered when calculating the oxygen value and monitored for a minimum temperature The actual temperature is continuously acquired and serves as an input ...

Page 18: ...s 5 4 Switching on and switching off When switching the sensor on or off temperature differences generate thermo electric voltages of up to 100 mV both positive and negative These can produce erroneous measurements during the heating up phase It is recommended to observe the heating up times specified in Engineering notes 5 5 Aging Due to aging the characteristics internal resistance and electrica...

Page 19: ... C 5 Measuring cell The measuring cell acquires differences in oxygen concentrations and delivers a Nernst voltage 6 Connecting head The connecting head contains the sensor s connection terminals and the temperature compensation element The compensation element delivers a current of about 1 µA K which represents the temperature inside the head The sum of head temperature and thermocouple temperatu...

Page 20: ...ensor 06 12 2017 7 Mounting and connecting the sensor 7 1 Mounting To simplify mounting in the chimney AGO21 mounting flange is available For mounting position refer to Mounting Instructions M7845 74 319 0866 0 The AGO21 must only be installed horizontally Figure 7 Figure 7 Mounting position of QGO21 ...

Page 21: ...to the PLL52 Note The signal lines require shielded 6 core cables with twisted pairs The shielding is to be connected to terminal GND of the PLL52 Open the cover only when the main switch is off so that both live and neutral conductors are disconnected There is a risk of burning since the measuring cell works at an operating temperature of 700 C U3 Figure 8 Connection QGO21 ...

Page 22: ...2 GND Q5 Q4 Figure 9 Connection diagram B1 Signal of oxygen measuring cell B2 Thermocouple voltage G2 Supply temperature compensation element GND Electrical ground for shielding M Electrical ground for signals B1 and B2 M Q4 Sensor heating with mains connection Q5 Sensor heating with mains connection U3 Signal of temperature compensation element Protective earth PE Legend ...

Page 23: ...mm 7845m01 0812 80 64 7 140 244 104 45 2x Pg9 A C B D Figure 10 Dimension QGO21 000Dx7 A Sensor head B Reference air slots C Flange gasket included D Sinter filter 7845m02 1111 48 51 90 64 Figure 11 Dimension AGO21 A SW41 11 2 45 A A A 7845m05 1111 Figure 12 Dimension AGO742870012 QGO21 000Dx7 Legend AGO21 AGO742870012 ...

Page 24: ... 10 Comparison table 06 12 2017 10 Comparison table Oil wet dry Gas wet dry 7845z04e 1112 Figure 13 Comparison table for different flue gas analysis devices in Note Additional humidity is not taken into account and may distort the measured value Example Urea injection ...

Page 25: ...a cell temperature of 700 C 16 Figure 4 Impact of the cell s temperature on the oxygen value 17 Figure 5 Nernst voltage as a function of the reference gas 18 Figure 6 Mechanical design of the oxygen sensor 19 Figure 7 Mounting position of QGO21 20 Figure 8 Connection QGO21 21 Figure 9 Connection diagram 22 Figure 10 Dimension QGO21 000Dx7 23 Figure 11 Dimension AGO21 23 Figure 12 Dimension AGO7428...

Page 26: ...s 18 Switching on and switching off 18 Dimension AGO21 23 AGO742870012 23 Dimensions 23 QGO21 000Dx7 23 F Flue gas guidance 19 H Heating 19 M Measuring 19 Mechanical design of the sensor 19 Mounting and connecting the sensor 20 Connection 21 Mounting 20 O Overview 12 R Reference air slots 19 S Safety notes 4 Commissioning notes 8 Disposal notes 11 Electrical connection 7 Engineering notes 6 Functi...

Page 27: ...en Sensor QGO21 CC1P7845en 12 Index 06 12 2017 Siemens AG Building Technologies Division Berliner Ring 23 D 76437 Rastatt Tel 49 7222 598 279 Fax 49 7222 598 269 www siemens com 2017 Siemens AG Building Technologies Division Subject to change ...

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