External
resistor
%
structure
Keypad and
format
Advanced
parameter
descriptions
Serial comms
temperature
Pr
11.65
100
0
Pr
11.62
Pr
11.63
t
Assuming that the full power discharge time is much shorter than the full power discharge period (which is normally the case) the values for Pr
11.60
and Pr
11.61
can be calculated as follows:
Power
=
---------------------------------------------------------------
Pr11.64
Energy
Power
Where Energy is the total energy that can be absorbed by the external resistor when its initial temperature is ambient temperature.
Disch
argeTime
(
Pr11.62
)
T
on
=
Energy
⋅
Pr
11.64
If the cycle shown in the diagram above is followed repeatedly, where the external resistor is heated to its maximum temperature and then cools to
ambient:
The average power in the resistor
T
on
Pr
11.62
T
Pr
11.63
where Tp is the full power discharge period (Pr
11.63
)
Energy
T
Energy
p
Disch
argePower
Pr11.63
T
p
=
----------------------------------------------
AveragePower
The temperature of the external resistor is monitored by the temperature accumulators (Pr
11.63
). When parameter Pr
11.62
reaches 100 % the drive
will trip ‘O.ht3’.
modelling the temperature of the resistor.
NOTE
If this is not entered correctly the power dissipated, and therefore the thermal protection model for the resistor will be incorrect. This could lead to the
resistor being operated beyond its thermal limits.
158
Mentor MP Advanced User Guide
www.onxcontrol.com
Issue Number: 4
11.64
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