MA-037 - CB Watch 3 Operating Manual
v7.0 - May 2020
Page 40 of 118
Effect of ambient temperature
The temperature compensation uses the ambient temperature value and the compensation
table entered in the previous section.
It requires the presence of an outside ambient temperature value, either from a dedicated
temperature sensor or from the gas sensor(s).
The temperature compensation is computed by shifting the timing alarm thresholds based
on the change induced by the recorded ambient temperature when the operation took
place compared to nominal 20
o
C. The change is extrapolated from the table.
Example below: the time threshold was entered for an ambient temperature of 20
o
C. At
lower temperatures, extra time needs to be allowed so the compensating time should be
0ms for 20
o
C and +3ms at -25
o
C in the first example.
Figure 57
–
Two examples of operating time temperature compensation values
Effect of DC supply voltage
The control line voltage compensation depends on the actual DC voltage being supplied to
the coil when the command is sent compared to the nominal DC voltage.
It requires the presence of the DC voltage measurement sensor to provide the measured DC
voltage information required.
The coil voltage compensation is computed by shifting the alarm thresholds based on the
percentage change (up or down) of the coil voltage measured when the operation took
place compared to the nominal voltage.
Example below: the closing time threshold was entered for a nominal DC voltage of 125V. At
90V, an extra 6.1ms needs to be allowed for closing, so the compensating time should be
0ms for 0% of nominal and an increasing positive value of 6.1ms for a voltage of 90V DC
(90/125=72% of nominal). Table values for every 10% change in V can be extrapolated from
these values here. Conversely, a negative value is used as the voltage gets higher.
Figure 58
–
Example of closing operating time changes with voltage changes