11 drive dimensioning – Lenze DSD User Manual

Page 356

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11

Drive Dimensioning

11.6

Inverters

356

Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23

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k

ol

Set inverter operation with increased continuous power.

Frequency inverters can be operated with rated power

(100 %) and increased rated power (120 %).

• During operation with increased rated power, an in-

creased permanent power but only a few overload re-

serves are provided. Possible limitations for this

operation: limited temperature range, use of a mains

choke, lower switching frequency.

f

ch

kHz

kHz

Switching frequency range

M-n

M-n characteristic of the motor

: saved characteristic

-: equivalent characteristic

A

th

~

%

%

Previously calculated thermal utilisation of the inverter

• Monitoring of the continuous current

Relevant topics:

Thermal utilisation (Ixt) ( 348)

Possible messages:

Max. thermal utilisation >100 % ( 466)

A

~

(I

max

)

%

%

Previously calculated utilisation of the inverter relative

to the max. output current

• Ratio of the required current to the max. output cur-

rent of the inverter.

Relevant topics:

Determination of the utilisation values of the inverter

( 346)

Possible messages:

Max. output current exceeded ( 465)

A

~

(I

max,I

/I

N,M

)

Utilisation of the inverter calculated in advance with ref-

erence to the ratio of the rated output current of the in-

verter and the rated motor current

• An overdimensioning that is too high, due to an unfa-

vourable current resolution will possibly result in con-

trol-oriented problems and an insufficient behaviour

with regard to smooth running.

Relevant topics:

Determination of the utilisation values of the inverter

( 346)

Possible messages:

Current resolution is not adapted to the motor

( 467)

I

rated

A

A

Rated output current of the inverter

I

max

A

A

Max. output current of the inverter

• The maximum output current depends on the mains

voltage and the heatsink temperature and is reduced

at low output frequencies.

Relevant topics:

Current derating for inverters ( 352)

Possible messages:

Max. output current exceeded ( 465)

Parameter

Unit

Description

Metric

Imperial

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