Nidec Digitax HD M751 Base - Technical Data; Drive Technical Data Overview; Output Current Ratings and Overload

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98 Digitax HD M75X Series Installation and Technical Guide
Issue Number: 5
6 Technical data
6.1 Drive technical data
6.1.1 Peak current duration for pulse duty applications
The maximum duration for the peak output current depends on the total rms output current for the complete profile. The curves illustrated in Figure 6-
1 to Figure 6-3 can be used to determine the maximum duration for the drive peak current when operating at different rms currents. The curves are
shown normalised to the drive nominal current rating in a 40 °C ambient.
For example when using the Digitax HD M75X - 01400042
Nominal current = 4.2 A, Peak current = 12.6 A
• When operating at an output current of 4.2 A (1 on the curve), the peak current 12.6 A is available for 0.25 s.
• If the peak current of 12.6 A is required for 4 seconds, the maximum normalised r.m.s. current is 0.5 x 4.2 = 2.1 A.
• If the peak current of 12.6 A is required for 8 seconds, the current preceding the overload should be 0 A for at least 60 seconds (i.e. overload
is only available from the cold condition).
Figure 6-1 Maximum duration for 300 % overload @ 8 kHz switching frequency, 40 °C ambient and 50/60 Hz output frequency
Figure 6-2 Maximum duration for 300 % overload @ 8 kHz switching frequency, 40 °C ambient and 0.1 Hz output frequency
A reduction in the peak current will extend the overload duration, the maximum duration for a 200 % and 150 % overload can be determined from
Figure 6-3.
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0.1 1 10
Normalised Irms
Time for Ipk (s)
Ipk, 8 kHz, 50/60 Hz
50/60 Hz 8 kHz 50/60 Hz, 8 kHz, Rear Duct Ipk, 8 kHz, 50/ 60 Hz, 50 C°
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0.1
0.2
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0.1 1 10
Normalised Irms
Time for Ipk (s)
Ipk, 8 kHz, 0.1 Hz