ABB Relion 670 series - Connections for 1 Ph High Impedance Differential Protection HZPDIF (87)

Pos Description
1 Scheme grounding point
It is important to insure that only one grounding point exist in this scheme.
2 Three-phase plate with setting resistors and metrosils. Protective ground is a separate 4 mm screw
terminal on the plate.
3 Necessary connection for three-phase metrosil set.
4 Position of optional test switch for secondary injection into the high impedance differential IED.
5 Necessary connection for setting resistors.
6 Factory-made star point on a three-phase setting resistor set.
The star point connector must be removed for installations with 670 series IEDs.
This star point is required for RADHA schemes only.
7 Connections of three individual phase currents for high impedance scheme to three CT inputs in the
IED.
7.1.3.2 Connections for 1Ph High impedance differential protection HZPDIF (87)
Restricted earth fault protection is a typical application for 1Ph High impedance
differential protection HZPDIF (87). Typical CT connections for the high impedance
based protection scheme are shown in figure 52.
1MRK 506 369-UUS - Section 7
Differential protection
Line distance protection REL670 2.2 ANSI 143
Application manual