Eaton COOPER POWER SERIES Installation, Operation And Maintenance Instructions

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Eaton COOPER POWER SERIES Installation, Operation And Maintenance Instructions Manual pdf 25 page image

Operating sequenceWhen the tap-changer is in the neutral position and thecontrol calls for a tap change, the following events occur.1. The motor is energized and rotor begins to move.2. The motor drives the Geneva drive.3. The pin and roller on the Geneva drive gear enters aslot on the main Geneva/contact drive assembly andthe main Geneva/contact drive assembly begins toindex.4. The holding switch closes to ensure the tap change willgo to completion. The control opens the initial circuit.The motor is energized only by way of the holdingswitch.5. The reversing switch pin on the main Geneva/contactdrive assembly begins to drive the reversing switcharm.6. One of the two main interrupting movable contactsslides out of engagement with the neutral stationarycontact and interrupts the circuit through that branch.7. The reversing switch arm rotates, which causes thereversing switch contacts to pivot. A bridge betweenthe neutral contact and a stationary contact connectedto one end of the series winding is thus established.No arcing occurs across the reversing switch contacts.When the reversing arm rotates, a logic switch istriggered.8. The main interrupting contacts slide over and ontothe number one stationary contact, making a bridgingposition from contact N to contact 1 by way of thereactor.9. The pin on the Geneva drive gear exits the mainGeneva/contact drive assembly slot. The main Geneva/contact drive assembly stops moving and is rotationallylocked.10. The holding switch opens and the motor isde-energized.11. The magnetic rotor of the AC synchronous motor orthe brake used with the AC induction motor stops theGeneva drive gear at mid-travel.12. The elapsed time from step 1 to step 11 isapproximately 250 ms.13. If the control issues another signal to index in the samedirection, the same sequence is repeated except thereversing switch is not actuated. The reversing switchdoes not move until the tap-changer is reversed andstepped the opposite direction back to neutral.14. If the tap-changer is switching from position 15 toposition 16, a normally closed limit switch is triggeredthat is connected in parallel with the logic switch. Boththe limit switch and the logic switch open up, so thatthe control cannot make a tap change past position 16.MaintenancePeriodic inspectionsStep voltage regulators are designed to provide many yearsof trouble-free operation. The usable life of a regulator isaffected by application, but can be extended when periodicinspections are performed. Maintenance and inspectionschedules will vary and can be different for the samevoltage regulator design depending upon system conditionsand loading. The best predictor of future maintenancerequirements is past experience.If past maintenance requirements are not known, a firstinspection of the tap-changer contacts and other mechanicalcomponents inside the tank should be carried out after10 years or 100,000 operations.Inspection of components inside the tank and maintenanceof voltage regulator mechanisms should include the itemslisted below. Any problems found should be resolved beforeplacing the units back into service. Consult the tap-changermanuals listed below or your Eaton representative fordetails on maintenance procedures.Stationary contacts●● Inspect the arcing tips for excessive erosion.●● Inspect the contact surface for pitting and scoring.●● Replace excessively worn contacts.Moveable contacts●● Inspect the contacts for adequate contact surface area.●● Run the tap-changer through all positions checking forproper alignment with stationary contacts.●● Replace excessively worn contacts.Reversing switch contacts and mechanism●● Inspect contacts for wear.●● Inspect mechanisms for damage.Stationary contact board and moveable contact arm●● Inspect for build-up of carbon on surfaces; wipe off anybuild-up with a rag.●● Inspect for signs of arcing or heat damage.●● Inspect the phenolic contact boards found on legacytap-changers for scratches.●● Upgrade the phenolic moveable contact arm to thepolymer version for the legacy QD8 tap-changer.21VR-32 Voltage Regulator with Quik-Drive™ Tap-ChangerInstallatIon, operatIon, and MaIntenance InstructIons MN225008EN February 2017