Magazine | Issue 2 2022 requirements result in the typical automated infeed transfer methods shown in Figure 1 (fast transfer, in-phase transfer, and transfer with under-voltage or a specific delay time). In the event of fast transfer, the MBT system attempts to execute a transfer before the amplitude difference and phase shift between the motor and the new infeed are too great. This is only possible under specific conditions and requires the quantities in the motor bus and the new infeed to be measured within one cycle. In addition, a circuit breaker can connect the new infeed within one cycle. The in-phase transfer method connects the motor bus to the new infeed as soon as the phase angle between the motor bus «RelaySimTest 4.1 can be used to ensure that the MBT system works properly in all situations.» 0 –π –2π InPhase Residual Voltage Fast Phase Di erence (radiare) Bus Voltage (p.u) Time Zone 2 Zone 3 1.0 0.5 0.33 0.0 Zone 1 Figure 1: Motor bus transfer zones: Fast transfer, in-phase transfer and residual voltage transfer 25
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