Rel302 Pilot System; Pilot System Type; Permissive Overreach Transfer Trip/Simplified Unblocking - ABB REL 301 Instruction Leaflet

I.L. 40-386.4
"Zone-2"
"Zone-2, Zone-3"
"dV or dI"
NOTE: See Section 2.4.10 for ∆V ∆ I definition.
2. 5

REL302 PILOT SYSTEM

NOTE: The external Pilot Enable Switch (P
2.5.1

Pilot System Type

As mentioned in Section 2.3.4, choice of system type is controlled by the setting "Syst Type".
Both the REL301/302 have system type selection settings as shown below:
• "Non Pilot"
• "Zone-1 Extension"
• "POTT"
• "PUTT"
• "Blocking"
The following settings are recommended for POTT and BLOCKING systems:
• "Osc Data"
• "Flt Data"
• "FDOGTime"
• "Pilot Ø" & "Pilot G"
• "Zone-1 Ø" & "Zone-1G"–
• "Zone-3 Ø" & "Zone-3G"–
• "Zone-3"
2.5.1.1 Permissive Overreach Transfer Trip/Simplified Unblocking (Figures 2-20, 2-21, 2-22)
If the system type setting "Syst Type" is set to "POTT", REL302 will perform either the POTT
scheme or the Simplified Unblocking scheme, depending on the applied pilot channel.
The basic operating concepts of a POTT scheme are:
1) Pilot distance measurement units PLTP and PLTG ("Pilot Ø" and "Pilot G") are set to
overreach the next bus.
2) Pilot channel is a frequency shift type device; its signal may be through either metallic wire,
leased telephone circuits, power line carrier, microwave or fiber optic channels.
3) Transmitter frequency should be different at each terminal: channel is normally operated
on a guard frequency; and the channel frequency will be shifted from guard to trip when the
pilot relay(s) are operated; and pilot trip is performed when the pilot relay(s) operate and
a pilot trip frequency signal from the remote end is received.
2-14
– data taken if Zone-2 units pick up or any trip action occurs
– data taken if Zone-2 or Zone-3 units pick up, or any trip action occurs.
– data taken if DI, DV, Zone-2 or Zone-3 units pick up, or any trip action
occurs
tion with the "Pilot" setting set to "Yes" to enable the pilot system.
–
–
–
–
–
–
–
–
–
–
E ) must have voltage applied in conjunc-
LT NA
3 zone distance (REL301 and REL302)
(REL301 and REL302)

Permissive Overreach Transfer Trip/Simplified Unblocking

(REL302 only)
Permissive Underreach Transfer Trip (REL302 only)
Directional Comparison Blocking (REL302 only)
Zone-2, Zone-3
Trip
3 cycles or longer
150% overreach the next bus
80% of the protected line
100% of the reversed line
Reverse Dir. (required setting)