Russelectric RMTD Series automatic transfer switch, 100-4000 A
Russelectric's base automatic line, with a published catalogue key and a 400 ms delayed transfer by design
Russelectric RMTD Series automatic transfer switch, 100-4000 A is one of 7 automatic transfer switches tracked in the SecondWatt catalogue, each with specifications, lead times and indicative secondary-market pricing.
Russelectric RMTD dossier: 100-4000 A ratings, the published catalogue key, a 400 ms delayed transfer, observed used pricing and inspection guidance.
RMTD is Russelectric's base automatic transfer switch line, and the catalogue number decodes from a published key: RMTD, then amperage, then poles, then a phase-sensing letter, then an enclosure letter. The manufacturer's own worked example reads RMTD1004CE for a dual operator 100 A four-pole wall-mounted unit, with B denoting automatic two-pole sensing, C denoting three or four pole, and the enclosure suffix running blank for open, VS for vertical switchboard, E for wall-mounted and EF for free-standing. The design choice that separates this line from its peers is the transfer itself. RMTD holds roughly 400 milliseconds between disconnecting one source and connecting the other, letting motor loads demagnetise before reconnection. That is a delayed break-before-make design rather than closed transition, and it is why the line suits motor-heavy industrial loads while genuinely interruption-free duty falls to other Russelectric products. The correction the backlog needs is positional. RMTD is not Russelectric's bypass-isolation flagship; that is RTS-03, RTS-30 at a 30-cycle rating, and RTBD with its closed transition RTBD-CT variant. The 30-cycle distinction is visible directly in the market data: a 300 A RTS-30 traded at 116.67 USD per ampere against RMTD units at 1.63 to 8.00, which is the widest specification premium anywhere in this category.
Who buys it
Data center, healthcare and industrial operators who standardised on Russelectric, and motor-heavy facilities that want the delayed transfer without paying for closed transition. Russelectric builds from two United States sites and had roughly 400 employees at the time of the Siemens acquisition, so this is a specialist manufacturer rather than a volume brand, and its used units concentrate with a handful of dealers.
Role in the data center
Utility-to-generator transfer on Russelectric-standardised sites where motor loads dominate. Critical bus duty belongs to the RTS-03, RTS-30 and RTBD bypass-isolation families rather than to this line.
Key specifications
| Ampere ratings | 100 to 4000 across 13 frame points A |
|---|---|
| Poles | 2, 3 and 4 |
| Transfer delay | about 400, delayed break-before-make ms |
| Withstand and closing at 100-400 A | 42,000 3-cycle at 480 V A |
| Withstand and closing at 1000-1200 A | 85,000 3-cycle at 480 V A |
| Withstand and closing at 1600-4000 A | 100,000 3-cycle at 480 V A |
| With current-limiting fuses | 200,000 across all frames A |
| Listing | UL 1008 |
| Enclosures | open NEMA style, VS vertical switchboard, E wall mounted, EF free standing |
| Controller | Model 2000 with 20 x 4 character LCD and 5 x 5 keypad |
| Communications | proprietary serial, RS-422 and RS-485 compatible, multidrop to 4,000 ft |
| Operating temperature | minus 20 to plus 70 degrees C |
| Dimensions and weight | 24-64 in H, 19-60 in W, 12.75-26.25 in D, about 390-3,600 lb |
| Catalogue key | RMTD plus amperage, poles, phase-sensing letter and enclosure letter |
Technical summary
Ampere ratings: 13 frame points from 100 to 4000 A Poles: 2, 3 and 4 pole Voltage: 480 VAC referenced in the published closing and withstand charts Transition: about 400 ms between disconnection and reconnection, a delayed break-before-make design Withstand and closing, 3-cycle at 480 V: 42 kA at 100-400 A, 65 kA at 600-800 A, 100 kA at 1600-4000 A With current-limiting fuses: all frames rated to 200 kA Listing: UL 1008, marketed on the highest published 3-cycle closing and withstand ratings Enclosures: NEMA 1 open style, vertical switchboard VS, wall-mounted E and free-standing EF Controller: Russelectric Model 2000 microprocessor with a 20 by 4 character LCD and a 5 by 5 keypad Communications: proprietary serial protocol, RS-422 and RS-485 compatible, multidrop to 4,000 ft Operating temperature: minus 20 to plus 70 degrees C; storage minus 25 to plus 85 degrees C Dimensions: 24-64 in high, 19-60 in wide, 12.75-26.25 in deep, about 390-3,600 lb shipping
Configurations and options
The typical build is a three or four pole automatic switch with the Model 2000 controller in a wall-mounted or free-standing enclosure. The bypass-isolation siblings add solenoid-interlocked bypass contacts that parallel the switch while mechanical interlocks open the load-break contacts, with the base mounted on casters for removal and an isolation handle disconnecting primary and control power.
Compatibility and dependencies
The 400 millisecond transfer delay is a design characteristic rather than a setting, so this line is unsuitable where an uninterrupted transfer is required. The communications protocol is proprietary and serial, which means integration into a modern building system needs a gateway rather than a native connection.
Pricing and availability
Published price range: $1,799 - $32,000 depending on frame and condition. Trend: flat Lead time, new: 24-40 weeks (category benchmark). Lead time, used or refurbished: Days to 4 weeks from dealer stock.
Lifecycle and maintenance
Manufacturers publish maintenance intervals for this equipment rather than a service life. The pattern across ASCO, Cummins and Kohler literature is consistent: a monthly electrical transfer test, an annual preventive visit covering enclosure cleaning, contact inspection and lug retorquing, and a lithium control battery replaced every two years on the lines that carry one. No manufacturer in this set publishes a mechanical or electrical endurance figure in operations, and ASCO's own manuals state only that the non-replaceable main contacts are designed to last the life of the switch. That absence is why a used unit is priced on evidence of exercise and on controller availability rather than on a cycle count.
Common failure points
- Main contacts — Arc erosion pits and can weld the contacts, so the switch fails to transfer or fails to break
- Controller board — Power supply instability or logic fault stops the switch communicating with the generator control
- Voltage sensing drift — Pickup and dropout thresholds drift, so the switch does not register a real source loss
- Actuator and springs — Solenoid or linear actuator failure, capacitor failure or spring fatigue leaves the switch mid-travel
- Terminations — Vibration and moisture loosen lugs and corrode terminals, producing heat at the connection
- Exercise neglect — A switch that has not transferred in months fails on the first real outage
Inspection checklist
Withstand and closing rating — match the nameplate WCR to the actual upstream device, because UL 1008 Edition 9-2022 does not let a specific-breaker rating carry over to a different breaker Rating convention — establish whether the WCR is specific-breaker or any-breaker time-based, commonly 3-cycle, since the 2 conventions are not interchangeable Ampere frame and poles — confirm the frame rating and whether the unit is 2, 3 or 4 pole Neutral configuration — a 3-pole solid-neutral switch dropped into a separately derived system will nuisance-trip ground-fault relays Transfer test under load — operate normal to alternate and back, the monthly test NFPA 110 requires, and time it against the 10-second Type 10 threshold Contact condition — inspect for pitting and erosion; discoloration is normal and the manufacturer instruction is to use light emery paper rather than a file Controller and firmware — identify the exact controller and confirm the part number is still catalogued, because a dead controller with no retrofit path scraps the unit Control power — confirm the control power source and replace the lithium backup cell, specified at a 2-year interval on some lines Sensing thresholds — verify pickup and dropout against the 90% voltage and 95% frequency minimums used in the published operation sequence Lug torque — retorque every cable lug to the manufacturer's table, because vibration and thermal cycling loosen terminations Enclosure type — confirm NEMA 1, 3R, 4, 4X or 12 against the installation environment, since an indoor unit cannot be redeployed outdoors Service records — request the monthly transfer logs and the annual load-bank record; NFPA 110 Level 1 sites also owe a 36-month, 4-hour test Exercise history — an unexercised switch is the documented failure driver, so establish when it last transferred under load Reconditioning claim — transfer switches are named among equipment that cannot be reconditioned under NEC 110.21(A)(2), so treat any refurbished listing as a labelling question Rigging and access — confirm weight and footprint; a 4,000 A frame runs about 2,250 lb across 60 by 92 by 72 inches
Procurement channels
Surplus Record carries almost all of the priced inventory, concentrated with a handful of dealers including Quantum Technology, Powerhouse Systems and Critical Infrastructure Group, and a meaningful share of listings are request-price rather than numbered.