ABB Relion 620 Series, Руководство по применению

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Section 3
RER620 application
RER620 63
Application Manual
3.5 Loop Control Module
The loop control module (LCM) enables the RER620 to perform automatic loop
restoration functions, commonly accepted as a means to significantly improve circuit
reliability and to provide more effective system operation. The LCM is designed to
implement a loop control scheme by providing switching operations of the recloser to
sectionalize or remove the faulted section from the distribution system. The LCM enables
a recloser to monitor up to two banks of three-phase voltages (6 potential transformers
total) and to consider them in controlling breaker operations.
A recloser loop control scheme typically utilizes a predetermined number of RER620
controlled reclosers installed in series between two substation feeder circuits. This
provides isolation of any faulted section within a given distribution circuit while
simultaneously re-establishing service to all customers unaffected by the faulted section
within a relatively short period. Loop control scheme are typically located at or near key
customers at various locations throughout the distribution system, or where reliability on
particular circuits is particularly poor.
A typical full implementation of a loop system consists of 3 type of reclosers:
• Sectionalizing reclosers
• Midpoint reclosers
• TiePoint recloser
An explanation of the function of each of these reclosers types is given in the section
below.
3.5.1 Sectionalizing Recloser
The Sectionalizing recloser is a normally closed recloser that opens in response to a
downstream fault condition or to a loss of phase voltage from an upstream circuit. The
sectionalizer is typically the first protective device on the distribution line outside the
substation. Various settings determine the Sectionalizing recloser's sensitivity to both
current and voltage conditions. By design, for permanent faults between the substation and
the Sectionalizing recloser, the Sectionalizing recloser will open after a program delay to
set up for the back feeding from the alternate source. This timer is set to expire prior to the
Midpoint and Tiepoint timers.
3.5.2 Midpoint Recloser
The Midpoint recloser also is normally closed. Unlike the Sectionalizing recloser,
however, it does not open in response to phase voltage loss. Instead, it supports loop
control by automatically altering the RER620 settings in accordance with changing
voltage conditions. Specifically, upon the expiration of it's under voltage timer, it will
switch to a new setting group to prepare for a back feed condition and for a period will go
into non-reclose mode. The reason for the nonreclose is that in the event the fault is
between the Sectionalizing unit and the Midpoint, it would be undesirable to have the