Functional Software description
72 DCS 500 Software Description
Alarm and tripping limits can be selected by means of four pa-
rameters
MODEL1.ALARM L (1407)
MODEL1.TRIP L (1408)
MODEL2.ALARM L (1506)
MODEL2.TRIP L (1507)
Initial values are selected so that the overloadability is quite high.
For example, the current must continuously be √120 * 100 = 109.5
% before alarm is given and for trippings the current must be √130 *
100 = 114 %.
Recommended value for alarm is 90...100% and for tripping
106...110%.
MODELx.ALARM L (xxxx) = (alarm %
2
/100)
MODELx.TRIP L (xxxx) = (trip %
2
/100)
Example. The tripping limit is 106% --> MODELx.TRIP L (xxxx) =
112
Thermal time
constant
Time constants for thermal models are given by two parameters
MODEL1.TC (1409)
MODEL2.TC (1608)
It has to be noted that the thermal time constant cannot be used di-
rectly when calculating the tripping time. Often the motor manufac-
turer presents a curve that defines how long the motor can be
overloaded with a certain overload factor. Parameters MODEL1.TC
(1409) and MODEL2.TC (1608) can be selected by means of figure
on the next page.
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