ABB 615 Series ANSI, Technical Manual

Page: 583 / 713

Section 8
1MAC050144-MB C
Measurement functions
576 615 series ANSI
Technical Manual
Figure 309: Functional module diagram
8.12.4.1 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.
However, when Phase mode is "Three Phase", all the monitored phase signal magnitudes,
defined with Phase supervision, have to fall below or rise above the limit setting to activate
the PICKUP output and the corresponding phase output, that is, all the monitored phases
have to be activated. Accordingly, the deactivation occurs when the activation requirement
is not fulfilled, that is, one or more monitored phase signal magnitudes return beyond their
limits. Phases do not need to be activated by the same variation type to activate the
PICKUP output. Another consequence is that if only one or two phases are monitored, it
is sufficient that these monitored phases activate the PICKUP output.
8.12.4.2 Variation detection
The module compares the measured voltage against the limit settings. If there is a
permanent undervoltage or overvoltage, the Reference voltage setting can be set to this
voltage level to avoid the undesired voltage dip or swell indications. This is accomplished
by converting the variation limits with the Reference voltage setting in the variation
detection module, that is, when there is a voltage different from the nominal voltage, the
Reference voltage setting is set to this voltage.
The Variation enable setting is used for enabling or disabling the variation types. By
default, the setting value is "Swell+dip+Int" and all the alternative variation types are
indicated. For example, for setting "Swell+dip", the interruption detection is not active and
only swell or dip events are indicated.
BLOCK
Variation
detection
Duration
measurement
Variation
validation
Recorded
data
TRIP
PICKUP
SWELLST
DIPST
INTST
V_A
V_B
V_C
I_A
I_B
I_C