Panametrics Sentinel User Manual page 58

Chapter 2. Initial Setup
2.6.1.3 Errors
To set limits for possible errors, see Figure 39 on page lix and consider the following:
Note:
In the event that one of the following errors exceeds its limit, a corresponding error notice, described in
Chapter 4, Troubleshooting, will be displayed by PanaView and Modbus. Also, the alarm relay will change
state and the 4-20mA output and the Frequency output will be able to be programmed to identify the
presence of an error.
• Soundspeed: The soundspeed % Theory is set to cover the range at which the gas soundspeed may vary as a
function of its composition, pressure and temperature. Setting the number too low may cause the meter to get
into an error mode and stop working. Setting the number too high may cause the meter to fail to detect
instrument malfunctions.
• Signal Strength Limits: The meter can operate in a very wide range of signal strength. The low limit should be
set to allow the Signal to Noise Ratio to be large enough to ensure that the meter will maintain the specified
accuracy. The upper limit needs to be set to ensure that the meter will not be overloaded and the signal be
undetected.
• Amplitude Limits: The steady state amplitude is 100%. In case of a sudden change in the system gain, it may
take time for the AGC to stabilize the amplitude to 100%. An error will be indicated if the amplitude exceeds the
limits.
• Velocity: The velocity limits should be set higher than the maximum possible flow.
• Acceleration: The meter is testing for a change in velocity differential between each set of two consecutive
velocity calculations. In some applications a sharp change in velocity is expected. In that case the meter
should be programmed with a higher value than the default, which is 1.5 m/s.
58 Sentinel™ User's Manual