ABB RELION 620 Series Technical Manual page 683

1MAC504801-IB E
8.3.4
8.3.4.1
620 series ANSI
Technical Manual
PQSS contains a blocking functionality. It is possible to block a set of function outputs or
the function itself, if desired.
Operation principle
The function can be enabled and disabled with the Operation setting. The corresponding
parameter values are "Enable" and "Disable".
The operation of the voltage variation detection function can be described with a module
diagram. All the modules in the diagram are explained in the next sections.
GUID-91ED3E3D-F014-49EE-B4B0-DAD2509DD013-ANSI V1 EN
Figure 341: Functional module diagram
Phase mode setting
PQSS is designed for both single-phase and polyphase ac power systems, and selection
can be made with the Phase mode setting, which can be set either to the "Single Phase" or
"Three Phase" mode. The default setting is "Single Phase".
The basic difference between these alternatives depends on how many phases are needed
to have the voltage variation activated. When the Phase mode setting is "Single Phase",
the activation is straightforward. There is no dependence between the phases for variation
pickup. The PICKUP output and the corresponding phase pickup are activated when the
limit is exceeded or undershot. The corresponding phase pickup deactivation takes place
when the limit (includes small hysteresis) is undershot or exceeded. The PICKUP output
is deactivated when there are no more active phases.
Power quality measurement functions
Section 8
677