De-Rating Information; Thermal Protection And Automatic De-Rating; Maximum Motor Cable Lengths - Siemens MICROMASTER Eco Reference Manual

ECO REFERENCE MANUAL
14.

DE-RATING INFORMATION

THERMAL PROTECTION AND
AUTOMATIC DE-RATING
Losses within the power module rise with
increasing switching frequencies, leading to
higher heatsink temperatures. If the inverter
operates outside its recommended ambient
operating temperature it would normally trip, with
an over-temperature fault code. To avoid such
nuisance tripping, the MICROMASTER
Eco/MIDIMASTER Eco automatically reduces it's
switching frequency ( e.g. from 16kHz to 8kHz).
This reduces the temperature of the heatsink,
enabling the application to continue running - trip
free. Should the load or ambient temperature
then reduce, the inverter will first check to see if it
is safe to increase the switching frequency again
and then do so.
See parameter P076 for a list of de-ratings
applicable to particular ratings.
Maximum cable lengths and derating with respect to load current
208/240V MICROMASTER Eco:
Un-screened cable
F = 16kHz
max
Current (I/I ) ECO1-110/2
N
1.5 200
1.4 200
1.3 200
1.2 200
1.1 200
1.0 200

MAXIMUM MOTOR CABLE LENGTHS

The tables shown below give an indication of the
maximum motor cable allowed to be connected to
the inverter without the use of additional output
chokes.
I is the motor current and I
current (P083). Many application do not require
150% overload i.e. I/I
may be reduced using P186 (instantaneous
current limit) offering the added benefit of driving
longer cable lengths.
For cable lengths greater than those specified in
the tables, an external choke is required.
ECO1-150/2 ECO1-220/2
Cable length (m)
200 185
200 200
200 200
200 200
200 200
200 200
is the nominal motor
N
= 1.5, therefore this ratio
N
Standard MICROMASTER Eco
units have a maximum value of
I/I = 1.5 (i.e. 150% overload).
N
ECO1-300/2 ECO1-400/2
185 185
200 200
200 200
200 200
200 200
200 200
D-R
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