Schneider Electric 58 TRX

Class 8839 58M Enclosed AC Drives

Application Information

170 09/2003

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 se lection

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 continuou s

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 req uiring

constant torque above 60 Hz base speed will

involve connecting the AC drive to a 46 0 V su pply

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 bu s

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 f actor 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 lim its

dependent upon the electric power distribution

system for industrial and commercial consumers.