specified by tReset since the previous one, the function is reset. All outputs are set to
0 (FALSE). If no pole slip at all is detected under interval of time specified by tReset
since the pickup signal has been set (for example a stable case with synchronism
retained), the function is as well reset, which includes the pickup output signal
(PICKUP), which is reset to 0 (FALSE) after tReset interval of time has elapsed.
However, the measurements of analogue quantities such as R, X, P, Q, and so on
continue without interruptions. Recommended setting of tReset is in the range of 6 to
12 seconds.
• NoOfSlipsZ1: Maximum number of pole slips with centre of electromechanical
oscillation within zone 1 required for a trip. Usually, NoOfSlipsZ1= 1.
• NoOfSlipsZ2: Maximum number of pole slips with centre of electromechanical
oscillation within zone 2 required for a trip. The reason for the existence of two zones
of operation is selectivity, required particularly for successful islanding. If there are
several pole slip (out-of-step) relays in the power system, then selectivity between
relays is obtained by the relay reach (for example zone 1) rather then by time grading.
In a system, as in Table 32, the number of allowed pole slips in zone 2 can be the same
as in zone 1. Recommended value: NoOfSlipsZ2 = 2 or 3.
• Operation: With the setting Operation OOSPPAM function can be set On/Off.
• OperationZ1: Operation zone 1 Enabled, Disabled. If OperationZ1 = Disabled, all
pole-slips with centre of the electromagnetic oscillation within zone 1 are ignored.
Default setting = Enabled. More likely to be used is the option to extend zone 1 so that
zone 1 even covers zone 2. This feature is activated by the input to extend the zone 1
(EXTZ1).
• OperationZ2: Operation zone 2 Enabled, Disabled. If OperationZ1 = Disabled, all
pole-slips with centre of the electromagnetic oscillation within zone 2 are ignored.
Default setting = Enabled.
• tBreaker: Circuit breaker opening time. Use the default value tBreaker = 0.000 s if
unknown. If the value is known, then a value higher than 0.000 is specified, for
example tBreaker = 0.040 s: the out-of-step function gives a trip command
approximately 0.040 seconds before the currents reach their minimum value. This in
order to decrease the stress imposed to the circuit breaker.
• VBase: This is the voltage at the point where the Out-of-step protection is installed.
If the protection is installed on the generator output terminals, then VBase is the
nominal (rated) phase to phase voltage of the protected generator. All the resistances
and reactances are measured and displayed referred to voltage VBase. Observe that
ReverseX, ForwardX, ReverseR, and ForwardR must be given referred to
VBase.IBase is the protected generator nominal (rated) current, if the Out-of-step
protection belongs to a generator protection scheme.
• InvertCTCurr: If the currents fed to the Out-of-step protection are measured on the
protected generator neutral side (LV-side) then inversion is not necessary
(InvertCTCurr = Disabled), provided that the CT’s orientation complies with ABB
recommendations, as shown in Table
32. If the currents fed to the Out-of-step
protection are measured on the protected generator output terminals side (HV-side),
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 473
Application manual
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