Operating Speed; Dimensioning The Motor For Variable Speed Application; General; Dimensioning With Abb Acs800 Converters With Dtc Control - ABB M2A Manual De Instalación E Usuario

conductivity of the connection provided by the steel base
should be checked by, for example, measuring the poten-
tial difference between the components.
More information about grounding and cabling of variable
speed drives can be found in the manual "Grounding and
cabling of the drive system" (Code: 3AFY 61201998).

5.7 Operating speed

For speeds higher than the nominal speed stated on
the motor's rating plate, ensure that either the highest
permissible rotational speed of the motor or the critical
speed of the whole application is not exceeded.
5.8 Dimensioning the motor for
variable speed application

5.8.1 General

In the case of ABB ACS800 converters with DTC control,
the dimensioning can be done by using the loadability
curves shown in paragraph 5.8.2 or by using ABB's
DriveSize dimensioning program. The tool is downloadable
from the ABB website (www.abb.com/motors&drives). The
loadability curves are based on nominal supply voltage.
5.8.2 Dimensioning with ABB ACS800
converters with DTC control
The loadability curves (or load capacity curves) presented
in Figures 5 and 6 show the maximum allowed continuous
output torque of the motors as a function of supply
frequency. The output torque is given as a percentage of
the nominal torque of the motor.
NOTE!
The maximum speed of the motor must not be
exceeded even if the loadability curves are given up to
100 Hz.
For dimensioning motors and protection types other than
those mentioned in Figures 5 and 6, please contact ABB.
5.8.3 Dimensioning with other voltage
source PWM-type converters
Preliminary dimensioning can be done by using following
guideline loadability curves, see Figures 7 and 8. These
guideline curves assume a minimum switching frequency
of 3 kHz. To ensure safety, the combination must either be
tested or thermal sensors intended for control of the
surface temperatures must be used.
NOTE!
The actual thermal loadability of a motor may be lower
than shown by guideline curves.
14 – EN ABB Motors and Generators | Low voltage Ex motor manual 01-2007

5.8.4 Short time overloads

ABB flameproof motors usually provide a possibility for
short time overloading. For exact values, please see the
motor's rating plate.
Overloadability is specified by three factors:
I Maximum short time current
OL
T The length of allowed overload period
OL
T Cooling time required after each overload
COOL
period. During the cooling period motor current
and torque must stay below the limit of allowed
continuous loadability.

5.9 Rating plates

The following parameters must be shown on the rating
plates of hazardous area motors intended for variable
speed operation:
– speed range
– power range
– voltage and current range
– type of torque (constant or quadratic)
– converter type and required minimum switching
frequency
5.10 Commissioning the
variable speed application
The commissioning of the variable speed application must
be done according to the instructions for the frequency
converter and local laws and regulations. The require-
ments and limitations set by the application must also be
taken into account.
All parameters needed for setting the converter must be
taken from the motor rating plates. The most often needed
parameters are:
– Motor nominal voltage
– Motor nominal current
– Motor nominal frequency
– Motor nominal speed
– Motor nominal power
Note: In case of missing or inaccurate information, do not
operate the motor before ensuring correct settings!
ABB recommends using all the suitable protective features
provided by the converter to improve the safety of the
application. Converters usually provide features such as
(names and availability of features depend on manufac-
turer and model of the converter):
– Minimum speed
– Maximum speed
– Acceleration and deceleration times
– Maximum current
– Maximum Torque
– Stall protection
WARNING
These features are only additional and do not replace
the safety functions required by the standards.