Functions
2.49 Auxiliary Functions
SIPROTEC, 7UM62, Manual
C53000-G1176-C149-7, Release date 03.2010
336
The following table shows the operating ranges for synchronous and asynchronous machines. For this, param-
eter 1108 ACTIVE POWER is set to Generator. „Normal condition“ shows the active power under normal op-
erating conditions: + means that a positive power is displayed on the protective device, – means that the power
is negative.
Table 2-20 Operating Ranges for Synchronous and Asynchronous Machines
The table shows that the operating ranges in generator and motor operation are mirrored around the reactive
power axis. The measured power values also result from the above definition.
If, for instance, the forward power monitoring or the reverse power protection is to be used in a synchronous
motor, parameter 1108 ACTIVE POWER must be set to Motor. This multiplies the actual active power (accord-
ing to the above definition) with –1. This means that the power diagram is symmetrical around the reactive
power axis and the interpretation of active power changes. This effect must be considered when evaluating the
metered energy values.
If for instance positive power values are to be obtained with an asynchronous motor, the current direction at the
allocated CT set (e.g. parameter 201 STRPNT->OBJ S1) must be reversed. Parameter 1108 ACTIVE POWER
remains in the default setting Generator. This means that because of the generator reference-arrow system,
the earthing of the CTs that must be entered in the device is the opposite of the actual earthing. This leads to
results that are comparable to those of a consumer reference-arrow system.
Synchronous generator Synchronous motor
Asynchronous generator Asynchronous motor
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