32 Chapter 5 - Electrical Connections
User Manual
5.7. Chokes and filters
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A choke can be fitted to the mains input to DVS drives to limit RMS input current. Inductance can be
provided either by a single phase choke or by a mains transformer.
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Contact your nearest TDE office for information on the use of sinusoidal output filters.
5.7.1. Mains input chokes
Table 5.7.1.1: Mains input chokes
Drive Tipo
Induttanza di rete Corrente
Corrente
Frequenza
Modello
[mH]
Nom. [A] Saturaz. [A]
[Hz]
025
3,8
7,6
50 / 60
037
5,5
11
50 / 60
055
7,5
15
50 / 60
075
10
20
50 / 60
Induttanza di rete monofase
Use of a mains choke is recommended for all drive models:
-
to extend the life of the intermediate circuit capacitors and improve the reliability of the input diodes;
-
to reduce harmonic distortion in the mains;
-
to reduce the problems caused by power feed from a low impedence line.
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Determine the nominal current of chokes on the basis of the nominal current of the standard motors
whose power ratings are specified in table 3.3.2.1.
5.7.2. Output chokes
DVS drives can be used with general purpose motors as well as motors specifically designed for inverter control. Motors
designed for inverter control normally have better insulation to withstand PWM voltages.
The following are examples of applicable reference standards.
Motors designed for control by inverters do not require special inverter output filters. Standard motors on the other hand, especially
those with long cables (typically longer than 30 metres) may need a choke on the inverter output to keep the voltage wave form
within specified limits.
The nominal current of these chokes must be approximately 20% greater than that of the inverter itself to compensate for
additional losses caused by modulation of the output wave form.
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At the drives nominal current and a frequency of 50 Hz, output chokes cause an output voltage drop of
about 2%.
