Скачать с ютуб PZL-Świdnik Mi-2 GTD-350W full engine start cycle current measurement в хорошем качестве

PZL-Świdnik Mi-2 GTD-350W full engine start cycle current measurement

PZL-Świdnik Mi-2 helicopter left engine full start cycle off external batteries. For powering the heli during two pre-start engine dry crankings and two full engine start sequences two automotive 12V heavy-duty starter batteries are used wired in series for 24V. Engines are "soft started" with a small value series resistance on spool-up with a current appr. 100Amps then full power is applied where inrush current peaks about 600Amps on the STG-3 starter-generator (Стартер-генератор СТГ-3). Interestingly a small amount of back feeding happens to the batteries at the end of the 30second start cycle. This is visible when the current draw on the current clamp changes polarity and displays a negative value. Reason for this is that the EMF of the starter-generator becomes higher than the battery voltage due to being accelerated by the engine at that point in time, actually the starter-generator changes state from motor operation to generator operation during the start cycle.