GE D90 Plus Instruction Manual page 308

CONTROL ELEMENTS
298
For proper operation, the zone 2 and 4 phase and ground distance elements must be
enabled and configured according to the principles of distance relaying. The line pickup
element should be enabled and configured to detect line-end-open or weak-infeed and
undervoltage conditions. If used by the scheme, the selected ground directional
overcurrent functions must be enabled and configured accordingly.
In single-pole tripping applications, the hybrid POTT scheme uses local fault type
identification provided by the phase selector together with information received from the
remote terminal. The scheme generates output operands
TX4) that are used to transmit the signal to the remote terminals. Choices of
POTT
communications channel include remote inputs, remote outputs, and telecommunications
interfaces. When used with telecommunications facilities the output operands should be
assigned to operate an output contact connected to key the transmitter and assert the
individual bits at the interface.
To make the scheme fully operational as a stand-alone feature, the output operands must
be configured to interface with other relay functions, in particular the output contacts. The
output operands are typically programmed to initiate a trip, breaker fail, and autoreclose,
and drive an annunciator indication as per user requirements.
When used in conjunction with the trip output element, the hybrid POTT scheme is pre-
configured to initiate trip, breaker fail and single-pole autoreclose actions.
Select the Settings > Protection > Control > Pilot Schemes > Hybrid POTT Scheme menu
item to access the hybrid permissive over-reaching transfer trip settings.
Figure 254: Hybrid POTT configuration settings
The following settings are available for the hybrid permissive over-reaching transfer trip
(hybrid POTT) scheme.
Function
Range: Enabled, Disabled
Default: Disabled
This setting enables and disables the hybrid permissive over-reaching transfer trip
(hybrid POTT) scheme.
PLUS
D90 LINE DISTANCE PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 7: PROTECTION
(HYBRID POTT TX1 through
HYBRID