Справочник Пользователя для Sierra Monitor Corporation 4501-05

 

 

The transmitter assembly should be replaced when it is determined that it is unreliable, noisy or cannot be 
adjusted for calibration.  This may occur due to age, corrosion or failed components. 
To replace the transmitter assembly: 

a.  Remove the cover of the main enclosure 
b.  Unscrew the two thumb screws in the top of the cover plate, lift the assembly and rotate 90

o

 to relieve the 

wiring service loop 

c.  Unplug the sensor connector from the transmitter 
d.  Remove the two wires from J1 terminals (see figure 4-2) 
e.  Reverse the preceding steps to install the new transmitter 
f.  Restore power and allow a minimum of 30 minutes for stabilization before re-calibration 

The gas sensor which is located inside the sensor assembly housing can be replaced without replacement of 
the housing.  The gas sensor needs replacement when: 



  It is no longer possible to obtain correct Zero and Span values 



  The “LOW SENS” message appears after calibration 



  The sensor output signal is noisy, causing erroneous gas level readings 

 
To replace the sensor: 

a.  Confirm that system power has been removed 
b.  Remove the gas sensor module enclosure cover, 
c.  Unscrew the two thumb screws in the top of the faceplate, lift the transmitter assembly and rotate 90

o

 to 

relieve the wiring service loop. 

d.  Unplug the sensor connector from the transmitter 
e.  Unscrew the old sensor assembly from the enclosure conduit hub.  Remove the sensor assembly with its 

harness 

f.  Unscrew sensor housing cover from the sensor 
g.  Carefully pull the old sensor straight up from the socket 
h.  Press the new sensor into the socket. 
i.  Reverse the preceding steps to install the sensor assembly. 
j.  Allow the new sensor to stabilize for a minimum of 30 minutes and then calibrate using the procedure in 

Section 6. 

Prior to system start-up or trouble shooting, the entire system should be visually inspected. The following are 
guidelines for that inspection: 

•  Controller installed in conformance to manufacturer’s instruction manual recommendations. 

•  All splices are soldered or via terminal block. 
•  Cabling is away from sources of electrical noise or RFI where possible. 

•  Module installation in conformance with this manual. 
•  Modules accessible for calibration.