Lenze i410 - Page 192

Speed
compensaon for protecng motors at low speed
The inverter has implemented a compensaon funcon for low speeds. If the motor is
operated with frequencies below 40 Hz, the speed compensaon in 0x2D4B:002 (P308.02)
must be set to "On [0]" (default). This seng ensures that the tripping me for the monitoring
is reduced at low speeds, in order to take the reduced self-cooling of AC motors into account.
The speed
compensaon for UL-compliant operaon must also be set to "On
[0]" in 0x2D4B:002 (P308.02).
If the speed compensaon is acvated, the maximum load rao for connuous operaon is
reduced as follows:
•
A
t an output frequency < 40 Hz: Reduced maximum load rao for connuous operaon
to 62.5 % + 37.5 % * output frequency [Hz] / 40 [Hz]
•
A
t an output frequency ≥ 40 Hz: No reduced release me
The following diagram shows the reduced release me with acvated speed compensaon.
•
Ma
ximum ulizaon 0x2D4B:001
(P308.01) = 150 %
•
Speed compensaon 0x2D4B:002 (P308.02) = "On [0]"
•
Load rao = 150 %
10
20
30
40
50
70
60
[s]
0
[Hz]
4 6 8
10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
2
Output frequency
Release time
40 Hz
60 s
30 Hz
≈ 41 s
20 Hz
≈ 31 s
10 Hz
≈ 23 s
Frequency
Release time
The following diagram shows the possible permanent load with acvated speed
compensaon without the monitoring being triggered.
•
Ma
ximum ulizaon 0x2D4B:001 (P308.01) = 150 %
•
Speed compensaon 0x2D4B:002 (P308.02) = "On [0]"
20
40
60
80
120
100
[%]
0
[Hz]
4 6 8
10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
2 0
Output frequency
Possible permanent load
40 Hz
110 %
30 Hz
99 %
20 Hz
90 %
10 Hz
79 %
Frequency
Load
In case of 0 Hz, only a load of 62.7 % (≈ 62.5 %) with regard to the load at 40 Hz or above is
possible (69
/ 110 * 100 % = 62.7 %). In case of a deviang seng in 0x2D4B:001 (P308.01),
the maximum possible motor load changes proporonately.
Maximum load rao for connuous operaon at an output frequency < = 40 Hz depending on
the maximum ulizaon 0x2D4B:001 and the output frequency.
•
R
educed maximum load rao for
connuous operaon = kf = 0.625 + 0.375/40 * output
frequency
•
Maximum load rao for connuous operaon [%] = 0.73 * kf * maximum ulizaon
0x2D4B:001 (P308.01)
Tripping me at an output frequency < 40 Hz and a load rao > maximum load rao for
connuous operaon
•
R
elease me [s] ≈ 15.9 / ((load rao/maximum ulizaon 0x2D4B:001
(P308.01) *kf )) –
0.724) [s]
Conguring the motor control
Mot
or protecon
Motor overload monitoring (i²*t)
192