Basler Electric BE1-11t - Manual (Page 59)

9424200995 Rev H 47
Auxiliary Undervoltage (27X) Protection
Four auxiliary undervoltage (27X) elements monitor the phase and auxiliary voltage applied to the
BE1-11t. An element can be configured to protect against undervoltage by monitoring neutral-shift
voltage, positive-sequence voltage, negative-sequence voltage, fundamental voltage on the Vx input, or
third-harmonic voltage on the Vx input.
The four, identical auxiliary undervoltage protection elements are designated 27X-1, 27X-2, 27X-3, and
27X-4. Element logic connections are made on the BESTlogic
™Plus screen in BESTCOMSPlus® and
element operational settings are configured on the Undervoltage (27X) settings screen in
BESTCOMSPlus. A summary of the logic inputs and outputs and operational settings appears at the end
of this chapter.
BESTCOMSPlus Navigation Path: Settings Explorer, Protection, Voltage, Undervoltage (27X)
HMI Navigation Path: Settings Explorer, Protection, Settings Group x (where x = 0 to 3), Voltage
Protection, Undervoltage 27X
Element Operation
Auxiliary undervoltage protection can be used to protect equipment from damage caused by phase
failure, positive/negative phase sequence, or phase unbalance.
Modes of Protection
Five modes of protection are available: 3V0, V1, V2, Vx Fundamental, and Vx Third Harmonic.
3V0 Mode
3V0 mode provides voltage unbalance protection in a three-phase system. The 3V0 measurement
increases as the three-phase voltages become unbalanced.
V1 Mode
V1 mode provides positive phase-sequence protection in a three-phase system. The V1 measurement
increases as the phase sequence is brought forward.
V2 Mode
V2 mode provides negative phase-sequence protection in a three-phase system. The V2 measurement
increases as voltage becomes unbalanced or the phase sequence is reversed.
Vx Fundamental Mode
Vx Fundamental mode provides ground offset detection on high impedance ground systems or phase
undervoltage protection in sync-check applications.
Vx Third Harmonic Mode
Vx Third Harmonic mode provides internal generator short detection.
Connections
Connections are made on the rear of the BE1-11t. The phase VT inputs (Va, Vb, Vc) are used when 3V0,
V1, or V2 mode is selected. The auxiliary VT input (Vx) is used when Vx Fundamental or Vx Third
Harmonic mode is selected. For an illustration of terminals, refer to the
Terminals and Connectors
chapter.
Sensing Configuration
When using the Vx input, setting the Aux VT Connection parameter provides the correct labeling of
settings and metering data found in BESTCOMSPlus and fault reports. The Aux VT Connection
BE1-11t Auxiliary Undervoltage (27X) Protection