Basler BE1-951 User Manual

3-2 BE1-951 Input and Output Functions 9328900990 Rev L
Zero-Sequence Voltage
When four-wire VT connections are used, the BE1-951 calculates the zero-sequence voltage (3V
0
). Zero-
sequence voltage measurement is not available when single-phase or three-wire VT connections are
used. The 27X and 59X can be set to monitor the zero-sequence voltage.
Negative-Sequence (V
2
) Voltage
Negative-sequence voltage is calculated from the fundamental component of the three-phase voltage
inputs. It is only available on three-phase, three-wire or three-phase, four-wire systems. V
2
is calibrated to
the phase-to-neutral base. Negative-sequence measurements can accommodate either ABC or ACB
phase-sequence.
Frequency Measurement
Power system frequency is monitored on the A phase voltage input or the AB voltage input when in three-
wire mode. When the applied voltage is greater than 10 volts, the BE1-951 measures the frequency. The
measured frequency is used by the 81 function and applies to all measurements and calculations.
Frequency Compensation
After measuring the frequency, the BE1-951 varies the sampling rate to maintain 12 samples per cycle
over a frequency of 10 to 75 hertz. If the voltage is too low for accurate frequency measurement or, if the
measured frequency is out of range, the ADC defaults to a sampling rate appropriate for the relay nominal
frequency setting. The sampling rate is adjusted every 250 milliseconds.
Nominal Frequency
Nominal frequency is set for 50 hertz or 60 hertz power systems. When the voltage is too low for reliable
frequency measurement, the ADC defaults to operation at the nominal frequency setting.
Power Measurement
The measured fundamental component of current and voltage as described previously in this section is
used to calculate the power per the following equations.
For four-wire VT connection:
() ()
(
)
CCCBBBAAA
IVIVIVWATTs Φ+Φ+Φ=
Φ
coscoscos
3
Equation 1
() ()
(
)
CCCBBBAAA
IVIVIVVARs Φ+Φ+Φ=
Φ
sinsinsin
3
Equation 2
xxx
IVwhere ∠−∠=Φ:
For three-wire VT connection:
(
)
(
)
CCCBAAAB
IVIVWATTs Φ+Φ=
Φ
coscos
3
Equation 3
(
)
(
)
CCCBAAAB
IVIVVARs Φ+Φ=
Φ
sinsin
3
Equation 4
xxyx
IVwhere ∠−∠=Φ:
For AN, BN, or CN VT connection:
()
xxx
IVWATTs Φ×=
Φ
cos3
3
Equation 5
()
xxx
IVVARs Φ×=
Φ
sin3
3
Equation 6
xxx
IVandtypengsensionbasedCorBAxwhere ∠−∠== φ ,,:

Basler BE1-951 Specifications

General

Brand	Basler
Model	BE1-951
Category	Surge Protector
Language	English