2 Engineering2.11 Motor connection48 DS7 Soft starter 09/16 MN03901001Z-EN www.eaton.com2.11.9 Cascade circuitThe DS7 soft starters can be used to start several motors in sequence.This requires the observance of a specific switching sequence (￫ section 7,“Connection examples”).2.11.10 Motors with power factor correction capacitorIf capacitors are to be used for power factor correction and thus to improvethe power factor, they must be connected to the mains side of the softstarter.The following Figure 31 shows on the right a safe arrangement.During the startup and stop phase (generalized phase control), the powerfactor correction capacitors are disconnected. After the start time (t-Start)elapses, they are connected via the TOR signal of the soft starter and thecapacitor contactor Q12, which disconnect them at the beginning of the stoptime (t-Stop).Figure 31: Reactive current compensated motorLeft: impermissible connection;Right: permissible connection￫ When starting several motors with one soft starter the thermalload of the soft starter (starting frequency, current load) must betaken into account.If the starts occur closely in succession, the soft starter must bedimensioned larger (i.e. the soft starter must be designed withan accordingly higher load cycle).￫ In networks with electronically controlled consumers (e.g. softstarters), the compensation devices must always be connectedwith a series inductance.MM1 3Q11Q21L1L2L3Q1L1 L2 L3T1 T2 T3MM1 3Q11Q21L1L2L3Q12TORQ1L1 L2 L3T1 T2 T3
