SERVICE MANUAL R5888B
QUADRAMHO Chapter 1
Page 1 of 27
Section 1. GENERAL
The Quadramho has been developed for use on medium to high voltage
transmission and distribution lines where traditionally switched distance schemes
have been used.
The relay is a full 3 zone distance scheme which eliminates the need for starting
and switching circuits, but which remains as compact as a switched relay because
it employs modern components and circuit techniques. A full distance scheme
allows better reliability and faster operating times than a switched distance
scheme.
Section 2. RELAY CHARACTERISTICS
There are two versions of the Quadramho to choose from, with the following
impedance characteristics:
Type A (mho) Zone 1, Zone 2 phase and ground fault : shaped partially
cross-polarised mho.
Zone 3, phase and ground fault : offset lenticular shape.
Type B (quad) Zone 1, Zone 2 ground fault : quadrilateral, with partially
cross-polarised directional line and load flow compensated
reach line.
Zone 3 ground fault : offset quadrilateral with load flow
compensated reach line.
Zone 1, Zone 2 phase fault : shaped partially cross-polarised
mho.
Zone 3 phase fault : offset circular mho.
See Figure 1 Appendix A, for examples of impedance
characteristics.
Note: Voltage transformer supervision and power swing blocking feature are
included with both models.
Section 3. SCHEMES AVAILABLE ON RELAY
There are 5 schemes available and each scheme can be selected as a three phase
tripping scheme or a single and three phase tripping scheme:
Basic three zone distance protection
Zone 1 extension scheme
Permissive underreach transfer tripping scheme
Permissive overreach transfer tripping scheme
Blocking scheme
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