Protection Signaling Schemes; Overview; Direct Under-Reaching Transfer Trip (Dutt); Permissive Under-Reaching Transfer Trip (Putt) - GE D60 Instruction Manual

9.3 PROTECTION SIGNALING SCHEMES

9.3PROTECTION SIGNALING SCHEMES
The D60 includes five common pilot-aided schemes:
•

direct under-reaching transfer trip (DUTT)

•

permissive under-reaching transfer trip (PUTT)

•

permissive over-reaching transfer trip (POTT)

• hybrid permissive over-reaching transfer trip (Hybrid POTT)
• directional comparison blocking
This scheme uses an under-reaching Zone 1 distance element to key a transfer trip signal to the remote end(s), where on
receipt, the DUTT pilot scheme operates without any additional supervision.
For proper operation of the scheme the Zone 1 phase and ground distance elements must be enabled, configured and set
per rules of distance relaying.
The scheme generates an output operand (DUTT TX) that is used to transmit the signal to the remote end. Choices of com-
munications channel include Remote Inputs/Outputs and telecommunications interfaces. When used with telecommunica-
tions facilities the output operand should be assigned to operate an output contact connected to key the transmitter at the
interface.
Note that the same protection signaling may be used by a breaker failure scheme, in which case the signal can be sealed
in by breaker fail for a time longer than the auto-reclose "reclaim" time which then prevents auto-reclose when not required.
A provision for an optional seal-in of the send signal is made to cover those situations where PLC (Power Line Carrier) sig-
naling is used and the signal must be transmitted in a potentially noisy situation due to the fault.
The scheme output operand (DUTT OP) must be configured to interface with other relay functions, output contacts in par-
ticular, in order to make the scheme fully operational. Typically, the output operand should be programmed to initiate a trip,
breaker fail, and auto-reclose, and drive a user-programmable LED as per user application.
This scheme uses an under-reaching Zone 1 distance element to key a transfer trip signal to the remote end where it is
supervised by the over-reaching Zone 2 distance elements.
For proper operation of the scheme the Zone 1 and 2 phase and ground distance elements must be enabled, configured
and set per rules of distance relaying.
The scheme generates an output operand (PUTT TX) that is used to transmit the signal to the remote end. Choices of com-
munications channel include Remote Inputs/Outputs and telecommunications interfaces. When used with telecommunica-
tions facilities the output operand should be assigned to operate an output contact connected to key the transmitter at the
interface.
The PUTT RX PICKUP DELAY timer can be used to ride through spurious PLC receive signals.
The scheme output operand (PUTT OP) must be configured to interface with other relay functions, output contacts in partic-
ular, in order to make the scheme fully operational. Typically, the output operand should be programmed to initiate a trip,
breaker fail, and auto-reclose, and drive a user-programmable LED as per user application.
9
This scheme is intended for two-terminal line applications only.
This scheme uses an over-reaching Zone 2 distance element to essentially compare the direction to a fault at both the ends
of the line.
Ground directional overcurrent functions available in the relay can be used in conjunction with the Zone 2 distance element
to key the scheme and initiate its operation. This provides increased coverage for high-resistance faults.
9-6
9.3.2 DIRECT UNDER-REACHING TRANSFER TRIP (DUTT)
9.3.3 PERMISSIVE UNDER-REACHING TRANSFER TRIP (PUTT)
9.3.4 PERMISSIVE OVER-REACHING TRANSFER TRIP (POTT)
D60 Line Distance Relay
9 APPLICATION OF SETTINGS

9.3.1 OVERVIEW

GE Multilin