Rockwell Automation Low-Voltage Switchgear and Controlgear - Manual (Page 120)

external conductors (I
e1
) and the phase currents (I
P1
, I
P2
) in comparison to the case described
above is a factor larger. This factor depends on the load of the motor. The relationships are as
represented in
Fig. 4.1-12 .
Fig. 4.1-11
Current distribution in delta-connected motors in normal operation and with loss of one phase
Fig. 4.1-12
Phase loss of a delta-connected motor. Current flow with symmetrical supply and with phase loss as a
function of the load
IEC 60947-4-1 defines the requirements on the performance of motor protective devices in the
event of a phase loss (
Tab. 4.1-5 ). For high quality motor protection temperature-compensated
devices with phase failure protection are standard.
LVSAM-WP001A-EN-P - April 2009 4-12