ABB REL650 series, Applications Manual

Page: 215 / 516

The protection measures the residual current out on the protected line. The protection
function has a directional function where the residual voltage (zero-sequence voltage) is
the polarizing quantity.
The residual voltage and current can be internally generated when a three-phase set of
voltage transformers and current transformers are used.
xx05000149_ansi.vsd
67N
ANSI05000149 V1 EN
Figure 101: Connection of polarizing voltage from an open (ANSI-broken) delta
The different steps can be described as follows.
Step 1
This step has directional instantaneous function. The requirement is that overreaching of
the protected line is not allowed.
1MRK 506 334-UUS A
Section 7
Current protection
209
Application manual