Eaton Cooper Power NR Series Maintenance Instructions Manual

Contents

Contact resistance*Standard: 750-875 mΩExtra Creepage (17 inch): 875-1000 mΩ20 kV (125 kV BIL): 845-945 mΩMoving contactsMinor pitting can be smoothed with crocus cloth. If contactsshow appreciable wear due to arc erosion, replace asfollows:1. Remove the round head screws and lockwashers thatsecure the moving contact bar to the contact arm.Remove the bar from the contact arm.2. Reassemble the new moving contact bar to thecontact arm and secure with round head screws andlockwashers. Apply one drop of Loctite® Threadlocker242® to each threaded hole of the contact bar prior toassembly.Stationary contactsSmooth minor pitting with crocus cloth. If contacts areexcessively eroded, replace as follows:1. Remove hex nut, lockwasher and flatwasher fromcontact stud. Loosen nut on bushing rod slightly andslip terminal lead from contact stud.2. Open flexible contact leads and remove contactretainer. Pull the stationary contact assembly andcontact roller from contact stud.3. Install contact roller within new contact assembly andmount on the contact stud. Install following parts inorder: contact retainer, flexible contact leads, terminalleads, flatwasher, lockwasher and hex nut. Tighten hexnut on bushing rod.4. With the moving contacts in the open position, thespace between the stationary contacts should measure0.281 ± 0.010 inch.ote:N The stationary contact assembly is normally pre-adjusted during manufacture to obtain this clearance.Bend the contact fingers as required if this spacing isnot within specified tolerances.Figure 6. Removing moving contact.Figure 7. Removing stationary contact.Moving ContactArmContact RetainingScrewsContact BarStationary ContactAssemblyContact RetainerContact StudFlexible ContactLeadCAUTIONBe sure not to pull contacts or contact structure outof alignment when tightening the jumper lead tothe bushing terminal rod. To test alignment, wet thecontacts with oil. Then, with the actuator mechanismprepared for a closing operation, push the contactsclosed by hand and hold for a few seconds. When themoving contacts are released, they should be pulledopen by the spring in the head mechanism. If not,adjust stationary contacts as described in Step 4 untilthey do so.7TYPE NR OIL SWITCH MAINTENANCE INSTRUCTIONS MN230001EN February 2016