Schneider Electric ALTIVAR 58 TRX - Manual (Page 170)

Class 8839 58M Enclosed AC Drives
Application Information
170
09/2003 © 2000–2003 Schneider Electric All Rights Reserved
When selecting and applying AC Drives, the
following items should be considered where they
are applicable. Proper selection and application of
an AC Drive is essential to ensure reliable
operation and maximum performance of the
connected motor load. Please consult Product
Data Bulletin SC100 R5/95 “Adjustable
Frequency Controllers Application Guide” for
further details.
1. AC Drive selection
2. Ambient temperature/altitude
3. AC Line & motor voltage
4. Power factor
5. Harmonics
6. Input currents with and without line reactors
7. Drive isolation transformer
8. Speed range & regulation
9. Accelerating torque
10. Dynamic braking
11. Follower signals
12. PI regulator
13. Bypass operation
14. Motor selection
15. Enclosure types
16. Relay contact ratings
AC Drive Selection
The Class 8839 58M Enclosed AC drive is
selected based on the connected motor full load
current. AC drives in this catalog are listed by
horsepower, voltage and maximum continuous
output current ratings that align to the latest NEC
ratings. The motor horsepower rating may be
used to select the AC drive, provided it’s full load
current does not exceed the maximum continuous
output current rating of the drive. When the motor
full load current does exceed the maximum
continuous output rating of the AC drive, a larger
one must be selected.
In multi-motor applications the sum of the motor
full load current, not horsepower must be used to
select the appropriate AC drive.
Ambient Temperature/Altitude
The AC Drive and connected motor is rated to
operate in an ambient temperature of 0–40
° C
(32–104 ° F), and deliver full rated horsepower
nameplate data. When ambient temperatures
exceed the 40
° C (104 ° F) operational ambient
environment, both the AC drive and motor must
be derated. For installations that require a higher
operating ambient, derate by one horsepower size
to a maximum of 50
° C (122 ° F).
The Class 8839 58M Enclosed AC drives are also
rated for up to 3,300 feet (1,000 meters) altitude
without derating. Above these ratings, the AC
drive must be derated by 1.2% for every 300 feet
(100 meters) up to a maximum of 6,600 feet
(2,000 meters). For conditions where altitude
exceeds 6,600 feet, special considerations apply.
Environment, application, loading, and ambient
operating conditions could extend altitude range.
AC Line & Motor Voltage
The Class 8839 58M Enclosed AC drives are
designed for operation under continuous rated
input power from 208 V, 230 V and 460 V line
voltages,
± 10% at 50/60 Hz. The selection tables
list the horsepowers available at the different
voltage ratings. Alternate line voltage
configurations are also available on a special
order basis. Consult the Drives Applications
Group for those applications.
Normally, input voltage and motor voltage will be
the same, however, certain applications requiring
constant torque above 60 Hz base speed will
involve connecting the AC drive to a 460 V supply
and connecting the motor for 230 V at 60 Hz. The
AC drive can be adjusted to provide 230 V out at
60 Hz and 460 V out at 120 Hz. If this mode of
operation is desired, the AC drive must be
selected based on the full load current at 230 V.
Power Factor
The Class 8839 58M Enclosed AC drive uses
bridge rectifiers which convert the fixed voltage
and frequency from the AC line to a fixed DC bus
voltage. Operation of the rectifiers does not cause
any additional displacement between the voltage
and current on the AC line feeding the AC drive.
This means that the displacement power factor
(power factor measured by the utility) will not be
degraded. Therefore, the AC drive power factor is
rated 0.95 or better (lagging) at all times.
Harmonics
Concerning the subject of harmonics, all types
of adjustable speed drives using power
semiconductors and switching power supplies will
produce harmonic currents, which will cause a
non-sinusoidal voltage in the power system. The
suggested guidelines for voltage and current
distortion are addressed in IEEE Standard 519-
1992 titled "IEEE Recommended Practices and
Requirements for Harmonic Control in Electrical
Power Systems", which suggests distortion limits
dependent upon the electric power distribution
system for industrial and commercial consumers.