User Guide

Honeywell Parameter Descriptions 69
10
If the motor's t6-time (t6 is the time in seconds the motor can safely operate at
six times the rated current) is known (given by the motor manufacturer) the
time constant parameter can be set basing on it. As a rule of thumb, the motor
thermal time constant in minutes equals to 2xt6. If the drive is in stop state the
time constant is internally increased to three times the set parameter value.
See also Figure 10.9.
Figure 10.9: Motor temperature calculation
10.9 AUTORESTART PARAMETERS (CONTROL PANEL: MENU PAR ->
P10)
10.2 AUTOMATIC RESTART, TRIAL TIME
The Automatic restart function restarts the frequency converter when the
faults have disappeared and the waiting time has elapsed.
The time count starts from the first autorestart. If the number of faults occurring
during the trial time exceeds three, the fault state becomes active. Otherwise
the fault is cleared after the trial time has elapsed and the next fault starts the
trial time count again. See Figure 10.10.
If a single fault remains during the trial time, a fault state is true.
105%
par. 9.7
Q = (I/I
T
)
2
x (1-e
-t/T
)
I/I
T
Trip area
Motor temperature
Time
Motor temperature
Time constant T
*)
*)
Changes by motor size and
adjusted with parameter 9.10
Fault/warning
Motor
current