Close-Circuit Design: Anti-Pumping, Spring-Charged Logic and Closing Permissives

A breaker close circuit must convert one valid command into one controlled closing operation—and refuse every other combination. Anti-pumping prevents repeated close attempts from a maintained command, but it does not replace spring-charge, position, earth-switch, racking, synchronism, lockout and DC-health permissives.

This article develops hardwired and IED-assisted close circuits for spring-operated MV breakers, covering command authority, anti-pumping variants, 52a/52b timing, charged indication, undervoltage, closing-coil duty, interlocks, fail-to-close logic and verification.

Executive rules

Define one authoritative close-permissive matrix for local, remote, automatic transfer, synchronising and test modes.
A maintained close command must cause at most one close attempt until command release/reset: prove anti-pumping in every command path.
Use breaker/manufacturer-defined mechanism contacts and sequence; do not substitute generic 52a/52b timing.
Require adequate stored energy/spring charged, breaker open, valid truck position, earth switch open and lockout reset as applicable.
Do not place safety-critical mechanical interlocks solely in software.
Calculate close-coil voltage/current at worst DC source, wiring/contact drop and temperature.
Verify relay/contact DC inductive make/carry/break duty and coil de-energisation.
Prevent a close pulse from being held on a coil after mechanism completion or failure.
Distinguish “command accepted,” “coil energised,” “mechanism moved” and “breaker closed” for diagnostics.
Fault-insert stuck commands, contact failures, low DC, uncharged spring and invalid interlocks at FAT/SAT.

1. Standards and manufacturer data

Reference	Role
IEC 62271-1:2017+AMD1:2021	Auxiliary/control supply and common switchgear framework
IEC 62271-100:2021+AMD1:2024	Breaker, operating mechanism and operation requirements
IEC 62271-200:2021+AMD1:2024	Assembly, withdrawable positions, interlocks and auxiliary circuits
IEC 60255-27:2023	Protection/control equipment product safety—not complete close-function logic
IEC 61082-1:2014	Clear circuit-document preparation
IEEE C37.11-2022	Breaker electrical controls where IEEE regime applies

Obtain close-coil voltage range, cold/hot resistance/current, minimum pulse, maximum energisation, mechanism/52a/52b/spring-contact sequence, anti-pumping circuit, motor duty and interlock interface from the exact breaker. The safest architecture often retains the manufacturer’s proven internal circuit and supplies clean external permissive/command contacts.

2. Define commands and authority

local panel pushbutton;
breaker-mounted local control;
remote SCADA/RTU command;
protection/reclosing or automatic transfer;
synchronising device/autosynchroniser;
maintenance/test command with primary circuit disconnected;
emergency/manual mechanical close, if provided and permitted.

For each, define selector mode, access/cyber authority, pulse/maintained behaviour, permissives, blocking, event record and reset. Remote mode must not silently disable required local safety interlocks. A mechanical emergency close may bypass electrical permissives; control it by design/procedure and clear labelling.

3. Closing-permissive matrix

Permissive	Reason	Implementation evidence
Breaker open	Avoid energising close coil on closed breaker	52b/mechanism contact with verified sequence
Spring/stored energy charged	Assure one full close operation	Manufacturer charge/ready contact
Truck valid	Prevent close in intermediate position	Mechanical/electrical service or test position logic
Earth switch open	Prevent energising an earthed circuit	Mechanical interlock plus supervised indication/logic
Lockout reset	Prevent re-energisation after major protection	86/mechanical/electrical reset status
Synchronism/dead-bus valid	Prevent unsafe out-of-phase close	Synch-check/voltage logic and VT health
DC/control healthy	Avoid weak/incomplete operation	Voltage/MCB/coil path supervision as required
Process permissives	Motor/transformer/coupler/transfer constraints	Approved functional logic and fail state

Not every application uses every row. Mark mandatory, mode-dependent and informational conditions, then define what happens when an input is bad, stale or contradictory.

4. Anti-pumping: required behaviour

If a close command remains present while the breaker closes and subsequently trips, the breaker must not repeatedly reclose (“pump”) from that same maintained command. A new attempt requires release/removal of the original close command or a defined reset/new pulse, plus restored permissives.

anti-pumping is usually implemented by a breaker/mechanism relay/contact self-hold/interruption scheme;
it must work for local, remote, automatic and synchroniser commands;
it must survive rapid trip during/after close and contact bounce;
it must not block a legitimate new command after release;
loss/restoration of DC with command held must not cause an unintended close;
software pulse shaping alone is insufficient if a hardwired maintained input can bypass it.

5. Common anti-pumping implementations

Breaker-integral anti-pump relay

A relay picks up with the close command, permits one coil energisation, then holds/blocks while the command remains. Preferred when supplied/tested with the breaker. External logic must not bypass it.

Pulse conversion/edge detection in IED or PLC

Converts a maintained command to a pulse and requires reset. Useful diagnostically but depends on power/firmware/input quality and still should feed a hardware/mechanism architecture that prevents repeated closes.

Command-source momentary contacts only

Not sufficient by itself: a stuck pushbutton, welded relay or SCADA command may remain asserted. Provide positive anti-pumping at the breaker/control circuit.

6. Spring-charging system

spring-charging motor voltage/current/inrush and feeder protection;
charge limit switch/cam sequence and anti-run/stall protection;
charged/not charged contacts and mechanical indication correspondence;
recharge start after close and required recharge time;
mechanical/manual charging and stored-energy release procedure;
motor duty/temperature under repeated operations;
alarm for failure to charge within time;
ability to trip when spring uncharged—normally trip energy is separately available, but confirm design;
closing blocked until manufacturer-defined full charge/ready state.

A spring-charged contact is not proof of adequate close-coil DC voltage or latch health. Treat stored energy, release coil and mechanism readiness as separate conditions/diagnostics.

7. Breaker auxiliary contacts and timing

52b typically enables the close circuit while breaker open and opens as mechanism closes;
52a confirms closed and can drive indication/interlocks/anti-pump sequence;
contact transition, bounce and pole/mechanism timing must match coil interruption;
truck position/contact plugs can make/break additional permissives;
do not use one low-duty auxiliary contact directly for excessive DC inductive current;
verify spare contact availability, rating and mechanical correspondence;
test adjusted contact timing after mechanism maintenance.

8. Close-coil voltage-drop design

Calculate at coil pickup/inrush:

V_coil,min = V_{DC source,min} − I_{close,max at case} × R_{complete loop,max} − ΣV_devices

minimum battery bus under end-of-discharge, charger outage and simultaneous operations;
positive/negative cable at maximum temperature and minimum area;
MCB/fuse, selector, permissive, output/interposing, 52b, terminals and plug drops;
coil resistance/current versus temperature/voltage and manufacturer pickup value;
maximum DC voltage and cold-coil current/contact duty;
minimum pulse and supply transient/dip.

Do not assume IEC’s requirement that a coil operate at a stated minimum supply percentage proves the project wiring will deliver that voltage. Verify at coil terminals.

9. Close output and interposing relay

DC make/carry/interrupt rating at actual voltage/current/L/R;
output pulse length and contact release;
interposing coil burden/pickup/dropout and contact rating;
suppression polarity/type and effect on release/anti-pumping;
failure modes: welded/open contact, output leakage, common card/supply;
contact series/parallel arrangement only if manufacturer-qualified;
minimum switching load for supervisory/logic contacts.

A coil is normally de-energised by mechanism/auxiliary contact after close. Verify the device interrupting the inductive current and its endurance; the command contact may remain closed until pulse ends.

10. Synchronism-check and dead-bus logic

source and bus VT availability/fuse/selection and phasing;
voltage magnitude, frequency/slip and phase-angle window;
dead-bus/dead-line definition and undervoltage security;
close-time compensation from command to contact touch;
breaker closing-time scatter and temperature/DC dependence;
bad/missing/quality input fail state;
operator bypass authority, indication, timeout and audit;
coupler/transfer interlocks preventing inadvertent source paralleling.

For ordinary radial feeders synchronism may not be required; for couplers/generators/two sources it can be essential. Do not enable dead-bus closing solely from one failed VT fuse.

11. Withdrawable positions and earth-switch interlocking

closing allowed only in fully service or fully test/disconnected positions as designed;
mechanical interlock blocks intermediate-position close/racking closed breaker;
earth switch and breaker/truck interlocks form a safe sequence;
electrical position inputs corroborate—not replace—mechanical safety;
secondary plug connected as required for test operations;
remote closing blocked during local maintenance/racking mode;
shutters/doors/access correspond to declared IEC 62271-200 design.

12. Close-circuit supervision and diagnostics

DC supply/MCB healthy;
close coil continuity and breaker plug where feasible;
spring charged and charge-motor fail/timer;
breaker position disagreement;
lockout/interlock block reason;
command received/accepted/rejected with cause;
close output/coil current and breaker closing time;
failure to close within a set time after valid command;
anti-pumping active/command stuck alarm.

A simple close-coil continuity path can be state-dependent like trip supervision. Publish coverage/blind spots and avoid monitor current that energises the close release.

13. Failed close and repeated-command handling

start timer only after a fully valid accepted close command;
confirm close by reliable 52a/mechanism and optionally current/voltage process state;
remove close output at designed pulse/auxiliary transition;
latch alarm/sequence-of-events with block reason and DC/charged state;
do not automatically repeat close unless an approved scheme explicitly permits it;
keep anti-pumping block until command release;
trigger maintenance/investigation for slow/low-current/partial mechanism motion.

14. Cyber and remote-command controls

role/authority and local–remote selector semantics;
select-before-operate/checkback where system uses it;
command validity/timeout/duplicate suppression;
IEC 61850/SCADA communication quality and fail state;
event logs with authenticated source and time;
test/simulation mode blocking and visible indication;
no bypass of hardwired safety interlocks by network command;
change control for logic/settings/SCL.

15. FAT/SAT negative-test matrix

Valid local/remote/automatic close in permitted test/service states.
Maintain/stick each command; verify one close only after trip until release.
Remove and restore DC while close remains asserted; verify no unintended close.
Test spring uncharged/charge fail, breaker closed, truck intermediate and earth switch closed.
Test lockout active, protection block and local–remote conflicts.
Test VT/synchronism/dead-bus invalid/bad states where applicable.
Measure close-coil voltage/current/pulse and closing time at minimum DC.
Simulate output/52b/52a contact failures and close timeout.
Verify SCADA/event/alarm/block-reason indication.
Restore all blocks/selectors/links and repeat functional trip/close sequence.

16. Frequent design errors

Error	Correction
Momentary pushbutton called anti-pump	Block repeated closes from any maintained/stuck command
Software pulse is sole protection	Retain proven breaker/hardwired anti-pump path
Charged contact bypassed remotely	Use approved ready contact in every close path
Close coil sized at battery nominal	Calculate actual minimum coil-terminal voltage
52b used without timing/contact duty	Verify exact mechanism sequence and DC inductive rating
Dead bus from one VT low	Use secure VT-health/dead-bus logic
Automatic retry after failed close	Alarm/block unless explicit risk-assessed scheme

17. Engineering deliverables

command/authority/mode and closing-permissive matrix;
complete close/anti-pump/spring-motor schematics;
manufacturer coil/mechanism/contact/timing data;
DC voltage-drop, protection and output-contact calculations;
synchronism/dead-bus and fail-state design where applicable;
withdrawable/earth-switch mechanical/electrical interlock logic;
close-circuit diagnostics/alarm/event definitions;
relay/PLC/SCL configuration baseline;
FAT/SAT positive/negative/failure test results;
commissioning timing/current baseline and maintenance criteria.

18. Close-logic safety invariants

Write invariants as testable statements independent of implementation. They remain valid when a relay, PLC or breaker is replaced:

no close in an intermediate truck position;
no electrical close with the associated earth switch closed;
one maintained command produces no more than one close attempt;
DC loss/restoration never creates a close without a new valid command;
a trip/lockout condition dominates a simultaneous close command;
test-position close cannot energise primary contacts;
bad/stale synchronism inputs fail to the approved safe state;
temporary bypass is authorised, time-limited, indicated and audit-logged.

Trace each invariant to mechanical design, hardwired circuit, software/SCL logic and a negative test. If two layers can disagree, define which one physically prevents the hazardous action.

References

Safety note: Close-circuit testing can energise a primary circuit and stored-energy mechanism. Establish isolation/earthing, breaker position, operations authority, exclusion zones and safe spring discharge/charging before applying commands or temporary test links.