Alstom iSTAT M355, Manual, Page: 43 / 154

User Manual M3x5/EN M/B
iSTAT M3x5
Page 41
Thermal function
A thermal function assures exponent thermal characteristic based on simulation of bimetal
meters.
Maximum values and time of their occurrence are stored in device. A time constant can be
set from 1 to 255 minutes and is 6 times thermal time constant (t. c. = 6 × thermal time
constant).
Example:
Mode: Thermal function
Time constant: 8 min.
Running MD and maximal MD: Reset at 0 min.
FIGURE 10-2: OPERATION OF THERMAL MD FUNCTION
Fixed window
A fixed window is a mode that calculates average value over a fixed time period. Time
constant can be set from 1 to 255 min.
»
Time into period
« as displayed in QDSP2 actively shows the remaining time until the end of
the period in which current MD and maximal MD from the last reset are calculated.
When displays for Pt(+/ − ), Qt(L/C), St, I1, I2 and I3 are updated, a new period and
measurement of new average values are started. »TIME IN A PERIOD« then shows 0 of X
min.
A new period also starts after a longer interruption of power supply (more than 1 s). If time
constant is set to one of the values of 2, 3, 4, 5, 6, 10, 12, 15, 20, 30 or 60 minutes, »TIME
IN A PERIOD« is set to such value that one of the following intervals will be terminated at a
full hour. In other cases of time constants, »TIME IN A PERIOD« is set to 0.
Figure above shows display of MD measurement for current I1. Running MD is displayed (0
mA), max. value of MD since last reset is displayed and its time of occurrence.
Example:
Mode: Fixed window
Time constant: 8 min.
Running MD and maximal MD: Reset at 0 min.