The Reinhausen RMV-1 is a load tap changer manufactured by Maschinenfabrik Reinhausen, the dominant global manufacturer of LTC equipment. It is an oil-immersed LTC used in Reinhausen-equipped power transformers across utility and industrial applications worldwide. The RMV-1 uses a selector switch and reversing switch design. Reinhausen is the active manufacturer for this unit and the primary source for OEM parts. Aftermarket contact components are also available from Southern Switch for selector switch and reversing switch contact replacement.
The selector switch on the RMV-1 uses a moving contact assembly that advances through tap positions by engaging stationary contacts at each tap. Inspect the moving contact assembly for wear at the contact surfaces and verify that contact spring pressure against the stationary contacts is adequate. The moving contact assembly on the RMV-1 is a multi-piece unit — inspect each component of the assembly and verify that all mechanical fasteners are secure. A loose moving contact assembly will exhibit inconsistent contact pressure across tap positions, producing position-specific contact resistance readings.
The selector switch stationary contacts engage the tap winding connections at each position. Inspect each stationary contact for surface condition, oxidation, and evidence of thermal stress. Stationary contacts that are operating with insufficient contact pressure from the moving assembly will show heat-related discoloration at the engagement zone even without arcing damage. Measure contact resistance at each tap position and record the values for trending between maintenance intervals. Progressive increases in contact resistance at specific tap positions identify developing contact problems before they become failures.
The reversing switch uses a moving contact assembly that engages left-hand and right-hand stationary contacts to reverse the polarity of the tap winding. The LH and RH reversing stationary contacts are separate parts on the RMV-1 — they are not a single assembly and can be replaced individually if only one shows unacceptable wear. Inspect both contacts for wear depth and surface condition at the engagement zone. Measure contact resistance in both the raise and lower positions as part of every maintenance test and compare to the baseline. An elevated reading in one direction but not the other identifies the problem stationary contact specifically.
The reversing switch moving contact assembly is the spring-loaded contact arm that makes and breaks with the LH and RH stationary contacts. Inspect the moving contact arm for wear at the contact surface and verify that the spring force is adequate for firm engagement in both positions. A reversing switch moving contact that has lost spring tension will not fully seat against the stationary contact, producing elevated contact resistance in the reversing switch position where that arm is engaged.
The RMV-1 is an oil-immersed LTC with a dedicated oil compartment separate from the main transformer tank. Sample the LTC compartment oil at each maintenance interval for dielectric breakdown voltage, moisture content, and dissolved gas analysis. Reinhausen specifies minimum dielectric breakdown voltage levels for continued service — LTC oil that has degraded below the minimum specification must be replaced before the transformer is returned to service. The LTC oil compartment should not communicate with the main tank; verify the compartment seals are intact during each maintenance inspection.
Reinhausen publishes operation-count intervals for the RMV-1 in the unit service documentation. UnderNERC PRC-005, utilities operating on a calendar-based program must maintain maximum six-year intervals for LTC-equipped transformers. Reinhausen LTCs in active transmission or distribution service with high tap change rates may reach operation-count limits before the calendar trigger. Review the operations counter at each scheduled outage and do not defer maintenance when the count has been reached regardless of calendar interval.
Southern Switch supplies RMV-1 contact components including selector switch and reversing switch assemblies. Contact us with your transformer nameplate and operation count for a quote.