Vacon 100X series, Applications Manual

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Parameters vacon • 138
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6
6.2.14 Protections
P3.9.1.2 E
XTERNAL
F
AULT
An alarm message or a fault action and message is generated by an external fault external
fault signal in one of the programmable digital inputs (DI3 by default) using parameters
P3.5.1.11 and P3.5.1.12. The information can also be programmed into any of the relay outputs.
P3.9.2.3 Z
ERO
S
PEED
C
OOLING
Defines the cooling factor at zero speed in relation to the point where the motor is running at
nominal speed without external cooling. See Figure 44.
The default value is set assuming that there is no external fan cooling the motor. If an external
fan is used this parameter can be set to 90% (or even higher).
If you change the parameter P3.1.1.4
(Motor Nom Currnt)
, this parameter is automatically re-
stored to the default value.
Setting this parameter does not affect the maximum output current of the drive which is deter-
mined by parameter P3.1.3.1 alone.
The corner frequency for the thermal protection is 70% of the motor nominal frequency
(P3.1.1.2).
Figure 44. Motor thermal current I
T
curve
P3.9.2.4 T
HERMAL
T
IME
C
ONST
This is the thermal time constant of the motor. The bigger the motor, the bigger the time con-
stant. The time constant is the time within which the calculated thermal stage has reached
63% of its final value.
The motor thermal time is specific to the motor design and it varies between different motor
manufacturers. The default value of the parameter varies from size to size.
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 2*t6.
If the drive is in stop stage the time constant is internally increased to three times the set pa-
rameter value. The cooling in stop stage is based on convection and the time constant is in-
creased. See Figure 46.
f f
n
Par.
ID706=40%
0
9129.emf
I
T
100%
Overload area
P
cooling
Corner freq