Siemens LMV5 Quick Start Manual page 181
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Also See for LMV5:
- Technical instructions (374 pages) ,
- Basic documentation (278 pages) ,
- Manual (39 pages)
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The PLL52 and the QGO20 Oxygen Sensor 6-3
The PLL52 in combination with the QGO20 O2 sensor is the heart of the O2 trim system.
The QGO20 produces millivolt signals that are read by the PLL52.
On the low voltage side the PLL52 translates these millivolt signals and sends the information
back to the LMV52 digitally over the CANbus.
On the high voltage side, the PLL52 regulates the heating element amperage to the QGO20 in
an effort to keep the QGO20 sensing element at approximately 1290
Three millivolt signals originate in the QGO20:
Nernst Voltage from the zirconium oxide O2 cell
O2 cell thermocouple signal
Temperature compensation element
These three signals produce an accurate, Wet %O2 value. The thermocouple signal is also
used to control the PLL52's output to the QGO20. Amperage and therefore the heat output of
the QGO20's heating element are varied by changing the resistance on the high voltage side of
the PLL52 module.
The low voltage wires from the QGO20 to the PLL52 should always be run separate from the
high voltage heating element wires that also run from the PLL52 to the QGO20.
Separate shielded cables or separate conduits for the high and low voltage wires going to the
sensor must be used.
Also, the PLL52 must be installed within 25 feet of the QGO20.
Figure 6-3.1 shows a cut-away of the QGO20 sensor.
Figure 6-3.1 Cut-away view of the QGO20 sensor
LMV5 QSG Rev 4
Sec 6 Pg 7
o
F.
terminals B1 and M
terminals B2 and M
terminals G2 and U3
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