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Introduction
ManufacturingCharacteristics
TheRingMainUnit(RMU)hasbeendesignedforratedvoltagesofupto24kVandratedcurrentsupto
630A.ItisfullyinsulatedinSF6gasthatisusedasinsulatingandswitchingmedium.
The gas insulated units are insensitive to environmental
inuences, e.g : to humidity, dirt, dust etc. It has a
compactself-supportingmetal-cladstructureanditismaintenancefree.
KeyFeaturesSafeforuserduetomultipleinterlockingsystem.Simpleoperationwithclearoperationguidance.
Maintenancefree
Stableinanyclimaticcondition(-25to40C)
Easy/convenientcableinstallation
Easyfusereplacement
AdvantagesofOurSF6InsulatedRingMainUnitsMinimizeslandarearequirementforsubstations.
Thecompactsizeenablesthedistributionsubstationstobelocatedneartotheloadcenters.Metalenclosureandgasprotectstheswitchgearinteriorcomponentsagainstenvironmentaldegradation
Canbreaksmallmagnetizingcurrentswithoutbuildingupsystemovervoltages.
ExtendedservicelifeforRMU.
MechanicalDesignGeneralDescriptionAstandard3functionRMU(2L+1T)comprisestwoincominglineandonetransformeroutlet.Other
conguration of RMU from one function up to 4 functions can be
supplied in accordance to customers
requirement.Theoperatingmechanismissimpleandreliablewithguaranteeofmorethan5000cyclesC-O-
Eandcompletewithessentialinterlocksforpreventingfaultyoperation;henceprovidingextremesafetyand
reliability. The fuse grounding, up and down stream, is obtained
by means of an additional moving contact
attheswitch-disconnector.
Built-inFeatures1. Switching Device
ThemaincomponentsinthepatentedSF6breakingchamberisthe3positionswitch-disconnector(close-
open-earth) operated by a control operating mechanism tted on
the front panel of RMU. The moving
contactpositionoftheswitch-disconnectorcanbeseenclearlyandvisuallythroughthetransparentwindows
(oneforeachpath)locatedonthefrontsideofRMU(optionalfeature).
2. Safety Interlocks
OurRMUisprovidedwiththenecessaryandreliablesafetyInterlocks.
AccessibilitytofusecompartmentonlywhenearthswitchisON.
TheearthswitchcanturnOFFandswitchdisconnectorcanturnONonlywhenthefusecompartment
coverisCLOSED.
TheswitchdisconnectorcanbeturnedONonlyafterthereplacementoffaultyfuseintheeventofa
fault.
TheswitchdisconnectorcanonlybeturnedONwhenearthswitchisOFF.
TheearthswitchcanonlybeturnedONwhenswitchdisconnectorisOFF.
3. Pressure Release Disc
Thepressuredevicewhicharemetallicallyseparatedfromthecableconnectionactasrupturejointforthe
case of internal excess pressure of the gas-lled compartment. It
is located at the rear side of the tank to
ensurethesafetyoftheoperatingpersonnelbyguidingthearcrelease.
4. Pressure
GaugeMonitoringdeviceusedtoindicatethepressureinsideSF6cubicle.
5. Voltage Indicator & Live Phasing
Indicationdevicetocheckthepresentofvoltageinphase.Voltageindicatorincorporatedwith3hubsfor
livephasingtest.
6. Mimic DiagramExemplarydesignofoperatingpanel
Allcomponentsconductingmediumvoltage
are insensitive to :
-airhumidity
- aggressiveatmosphere
-dirt
-dust
SF6 properties:
-Extremelyhighinsulatingcapacity
- An inert, non-combustible media with
highdielectricproperty.
- Nocontactoxidation
Maximum operating safety due to :
- Lowgaspressurization
- Excellent gas-proong
-Highinductivebreakingcapacity
TelecontrolFeaturesTheRMUisdesignedtoadaptfortelecontrol
system and can be equipped with:
Motorizedswitchingcontrol
Switchconditionindication&faultindication
Emergencytrippingfortransformerfeeder.
The above featured will help to:
Improvetheservicequalitybyreducingthe
outagetime
Reducetheoperatingcostbyallowingfaster
network reconguration after fault event.
Allowsgreatersafetyandcomforttopersonnel
usingnetworkoperationtomonitorand
control.
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RMU SpecicationsElectrical Features
Line Feeder
Transformer Feeder
Optional features
1. Transparent Visualization window
Visible physical separation of switch disconnector inside the
apparatus
2. Motorized Switching Control
The switching operating mechanism includes a space that is
reserved for motorized control.
Installation exibility:
Factory pre-installed
On site installation without de-energizing the RMU
3. Switch Condition Indication
The switch operating mechanism includes a space that is reserved
for auxiliary switch. The switch condition
can be detected through the auxiliary contacts for remote
monitoring purposes.
4. Fault Indication
The RMU reserves space for mounting various type of CT &
Fault Indicator. Both the earth fault & phase
to phase fault can be detected depending on type of the CT and
Fault Indicator being is used. In the event
of fault, the signal is sent to Master Station through Remote
Terminal Unit (RTU) for rapid network
conguration.
5. Emergency Tripping for Transformer Feeder
The RMU is provided for shunt trip opening release which can
operate from remote. All modern
transformers are provided with sensing devices to forecast
probable disaster. In the event of any abnormality
sensed by these special devices, the emergency tripping can then
come into operation to prevent major
disasters.
6. Zero Voltage Detection
An indicator showing the system malfunction through lightning
ash symbols.
7. Short Circuit Indicator
Three indicator with symbol L1, L2, L3 are displayed separately
and can be equipped with:
Manual resetEarth fault indicator
Arc resistant protection cover which
protects cable connections.
RMU (1T + 2L) RMU (1T + 1L)
*IP 54 for outdoor application is available upon request.
**Rating for switch-fuse combination. The fuse housing can
accommodate up to 200A DIN type current limiting fuses.
Closed (ON) Open (OFF) Earthed
RMU (1T)
RMU (1L)
Busbar Busbar Busbar
Cable Feeder Cable Feeder Cable Feeder
Earthing Earthing Earthing
