Power System; Signal Sources - GE N60 Instruction Manual

SYSTEM SETUP

5.5.2 Power system

SETTINGS  SYSTEM SETUP  POWER SYSTEM
 POWER SYSTEM

The power system
cannot be measured from available signals. This can happen if the signals are not present or are heavily distorted. Before
reverting to the nominal frequency, the frequency tracking algorithm holds the last valid frequency measurement for a
safe period of time while waiting for the signals to reappear or for the distortions to decay.
The phase sequence of the power system is required to properly calculate sequence components and power parameters.
The
PHASE ROTATION
actual system phase sequence, either ABC or ACB. CT and VT inputs on the relay, labeled as A, B, and C, must be connected
to system phases A, B, and C for correct operation.
The
FREQUENCY AND PHASE REFERENCE
phase angle reference. The AC signal used is prioritized based on the AC inputs that are configured for the signal source:
phase voltages takes precedence, followed by auxiliary voltage, then phase currents, and finally ground current.
5
For three phase selection, phase A is used for angle referencing (
phase signals is used for frequency metering and tracking (
fault, open pole, and VT and CT fail conditions.
The phase reference and frequency tracking AC signals are selected based upon the Source configuration, regardless of
whether or not a particular signal is actually applied to the relay.
Phase angle of the reference signal always displays zero degrees and all other phase angles are relative to this signal. If the
pre-selected reference signal is not measurable at a given time, the phase angles are not referenced.
The phase angle referencing is done via a phase locked loop, which can synchronize independent UR-series relays if they
have the same AC signal reference. This results in very precise correlation of phase angle indications between different UR-
series relays.
FREQUENCY TRACKING
applications.
The frequency tracking feature functions only when the N60 is in the "Programmed" mode. If the N60 is "Not
Programmed," then metering values are available but can exhibit significant errors.
NOTE

5.5.3 Signal sources

SETTINGS  SYSTEM SETUP  SIGNAL SOURCES  SOURCE 1(6)
 SOURCE 1

5-114
NOMINAL FREQUENCY:

60 Hz
PHASE ROTATION:

ABC
FREQUENCY AND PHASE

REFERENCE: SRC 1
FREQUENCYTRACKING:

Enabled
value is used as a default to set the digital sampling rate if the system frequency
NOMINAL FREQUENCY
setting matches the power system phase sequence. Note that this setting informs the relay of the
setting determines which signal source is used (and hence which AC signal) for
is set to "Disabled" only in unusual circumstances; consult the factory for special variable-frequency
SOURCE 1 NAME:

SRC 1
SOURCE 1 PHASE CT:

None
SOURCE 1 GROUND CT:

None
N60 NETWORK STABILITY AND SYNCHROPHASOR MEASUREMENT SYSTEM – INSTRUCTION MANUAL
Range: 25 to 60 Hz in steps of 1
Range: ABC, ACB
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
Range: Disabled, Enabled
), while Clarke transformation of the
V = V
ANGLE REF A
  3 
V = 2V V V
– –
FREQUENCY A B C
Range: up to six alphanumeric characters
Range: None, F1, F5, F1+F5,... up to a combination of
any 6 CTs. Only Phase CT inputs are displayed.
Range: None, F1, F5, F1+F5,... up to a combination of
any 6 CTs. Only Ground CT inputs are displayed.
CHAPTER 5: SETTINGS
) for better performance during