{"product_id":"castair-automatic-two-compressor-alternator-relay-460-volt-alt460","title":"Castair Automatic Two Compressor Alternator Relay 460 Volt ALT460","description":"\u003cp\u003eThe \u003cstrong\u003eCastair ALT460\u003c\/strong\u003e is a 460-volt automatic alternator relay for two-compressor systems on three-phase electrical service. It automatically manages the lead\/lag operation between two compressors sharing a common air supply — alternating which unit runs as the primary each cycle so both machines accumulate equal operating hours over time. This is the relay-only version: no enclosure included. If you want the relay pre-mounted in a panel enclosure, see the ALT460M.\u003c\/p\u003e\n\n\u003cp\u003eThe 460V rating puts this relay in industrial territory. Three-phase 460V motors are the standard for compressors above roughly 10 HP in manufacturing plants, fleet yards, large collision centers, and heavy commercial facilities. If your compressor motors run on 460V (also labeled 440V or 480V in some installations — verify against your relay specifications), the ALT460 is the correct unit. Installing the 230V version on a 460V circuit is a wiring error that will destroy the relay and may damage the compressor motors.\u003c\/p\u003e\n\n\u003ch2\u003eWhy Three-Phase Facilities Need Alternator Relays\u003c\/h2\u003e\n\n\u003cp\u003eHigh-horsepower three-phase compressors in industrial settings run hard. They are often the backbone of a production air system, running during every shift, every day. In a duplex installation — two compressors sharing a common header or storage system — an alternator relay is not optional. It is how you protect the investment in both machines.\u003c\/p\u003e\n\n\u003cp\u003eThree specific problems the ALT460 solves:\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUnequal Wear:\u003c\/strong\u003e Without alternation, whichever compressor happens to be wired as the primary runs most of the hours. A 460V industrial compressor can cost $5,000 to $15,000 or more. Running one machine to failure while the second stays nearly new is not a maintenance strategy — it is an expensive mistake. The ALT460 prevents this by automatically rotating lead\/lag designation every cycle.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDuty Cycle Compliance:\u003c\/strong\u003e Every compressor manufacturer specifies maximum duty cycles — the maximum percentage of time the unit should run continuously. Heavy production air demand in a manufacturing plant can push a single compressor well past its rated duty cycle. The ALT460 shares that load across two machines, keeping each within manufacturer-specified limits. This is relevant for warranty compliance on new compressors.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eActual Redundancy:\u003c\/strong\u003e A second compressor is only useful as backup if it is maintained and ready to run. If the lag unit sits idle for months, its oil degrades and it may not start reliably when the primary goes down. The ALT460 keeps the second unit active and exercised, so the redundancy is real, not theoretical.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eHow the ALT460 Works\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLead Compressor Start:\u003c\/strong\u003e When system pressure drops below the cut-in setpoint, the lead compressor starts. The lag unit remains off.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLag Compressor Activation:\u003c\/strong\u003e If demand exceeds the lead unit's capacity and pressure continues to drop, the relay brings the lag compressor online to assist. Both units run until pressure recovers.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAutomatic Alternation:\u003c\/strong\u003e After each cycle, the relay swaps lead and lag designations. The unit that just ran as lead becomes lag on the next cycle. No manual input, no rotation schedules, no relying on technicians to remember which machine ran last.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003e460V Three-Phase Operation:\u003c\/strong\u003e Rated for 460V three-phase electrical service. Confirm your compressor motor voltage rating and panel supply voltage before ordering.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eFeatures\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003e460V Three-Phase Rated:\u003c\/strong\u003e Designed for industrial 460V electrical systems — the correct unit for three-phase compressor installations above 230V\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAutomatic Lead\/Lag Swap:\u003c\/strong\u003e No manual intervention — relay alternates lead\/lag designation automatically after each pressure cycle\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDual Compressor Start Coordination:\u003c\/strong\u003e Manages sequenced start and stop for both units, preventing simultaneous starts that spike current draw\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRelay-Only Format:\u003c\/strong\u003e The ALT460 is the relay unit without an enclosure. Install it in your own panel, junction box, or control cabinet. For a pre-mounted panel assembly, order the ALT460M.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompatible with Castair Control Accessories:\u003c\/strong\u003e Integrates with Castair hour meters (HRM75, HRM50), time delays (TD100), and low oil controls (6304, 6304B) for a complete duplex compressor control system\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCastair Manufacturing:\u003c\/strong\u003e Designed and built by Cast Air in Minnesota, a manufacturer specializing in duplex and industrial compressor controls\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhat's in the Box\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003eCastair ALT460 automatic alternator relay (relay unit only, no enclosure)\u003c\/li\u003e\n  \u003cli\u003eManufacturer documentation and wiring diagram\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003eNote: The ALT460 is a relay-only unit for integration into your own panel or control cabinet. If you need the relay pre-mounted in an enclosure ready for wall installation, order the ALT460M. Installation by a licensed electrician is required — this is a line-voltage three-phase control component.\u003c\/p\u003e\n\n\u003ch2\u003eAvailable Configurations — Full Matrix\u003c\/h2\u003e\n\n\u003cp\u003eCastair makes four alternator relay configurations to match your voltage and installation format:\u003c\/p\u003e\n\n\u003ctable\u003e\n  \u003cthead\u003e\n    \u003ctr\u003e\n      \u003cth\u003eModel\u003c\/th\u003e\n      \u003cth\u003eVoltage\u003c\/th\u003e\n      \u003cth\u003eFormat\u003c\/th\u003e\n      \u003cth\u003ePrice\u003c\/th\u003e\n      \u003cth\u003eBest For\u003c\/th\u003e\n    \u003c\/tr\u003e\n  \u003c\/thead\u003e\n  \u003ctbody\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003eALT230\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003e230V\u003c\/td\u003e\n      \u003ctd\u003eRelay only — you supply enclosure\u003c\/td\u003e\n      \u003ctd\u003e$398.86\u003c\/td\u003e\n      \u003ctd\u003e230V systems, installing into existing panel or custom control cabinet\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003eALT230M\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003e230V\u003c\/td\u003e\n      \u003ctd\u003eRelay pre-mounted in panel enclosure\u003c\/td\u003e\n      \u003ctd\u003eCall for pricing\u003c\/td\u003e\n      \u003ctd\u003e230V systems, clean permanent wall-mount installation without enclosure fabrication\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\n\u003cstrong\u003eALT460\u003c\/strong\u003e (this unit)\u003c\/td\u003e\n      \u003ctd\u003e460V\u003c\/td\u003e\n      \u003ctd\u003eRelay only — you supply enclosure\u003c\/td\u003e\n      \u003ctd\u003e$398.86\u003c\/td\u003e\n      \u003ctd\u003e460V three-phase systems, installing into existing panel or control cabinet\u003c\/td\u003e\n    \u003c\/tr\u003e\n    \u003ctr\u003e\n      \u003ctd\u003e\u003cstrong\u003eALT460M\u003c\/strong\u003e\u003c\/td\u003e\n      \u003ctd\u003e460V\u003c\/td\u003e\n      \u003ctd\u003eRelay pre-mounted in panel enclosure\u003c\/td\u003e\n      \u003ctd\u003eCall for pricing\u003c\/td\u003e\n      \u003ctd\u003e460V three-phase systems, clean permanent wall-mount installation\u003c\/td\u003e\n    \u003c\/tr\u003e\n  \u003c\/tbody\u003e\n\u003c\/table\u003e\n\n\u003cp\u003eVoltage is determined by your compressor motor nameplates and your electrical panel supply. Format (relay-only vs. mounted) is a matter of your installation setup. Do not mix voltages. Call 866-217-0063 if you need help confirming the right unit for your system.\u003c\/p\u003e\n\n\u003ch2\u003eWhen Does a Facility Need This vs. Stepping Up or Down\u003c\/h2\u003e\n\n\u003ch3\u003eThe ALT460 is the right choice if:\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eYou are running two compressors on 460V three-phase service with a shared air header or storage system\u003c\/li\u003e\n  \u003cli\u003eYour installation involves a custom control panel or existing cabinet where you are integrating the relay alongside other components\u003c\/li\u003e\n  \u003cli\u003eYou want to equalize wear across both compressors without manual tracking or rotation schedules\u003c\/li\u003e\n  \u003cli\u003eYou are building a new duplex installation and specifying the correct control components from the start\u003c\/li\u003e\n  \u003cli\u003eYour compressor manufacturer's warranty specifies a maximum duty cycle that demands load-sharing between two units\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eThe ALT460M is better if:\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eYou want a finished, self-contained panel assembly ready to mount and wire without enclosure fabrication\u003c\/li\u003e\n  \u003cli\u003eYour installation environment requires enclosed electrical components — dusty mechanical rooms, areas with moisture exposure, or anywhere an open relay is not appropriate\u003c\/li\u003e\n  \u003cli\u003eYou want a professional, permanent-looking control installation without custom panel work\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eYou need the 230V version (ALT230 or ALT230M) if:\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eYour compressor motors run on 230V service — verify on the motor nameplate\u003c\/li\u003e\n  \u003cli\u003eThe 460V and 230V versions are not interchangeable — check motor voltage and panel service voltage before ordering\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eYou do not need an alternator relay if:\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eYou have only one compressor — this relay is specifically for two-compressor systems\u003c\/li\u003e\n  \u003cli\u003eYour two compressors are on completely independent circuits and systems with no shared load — though equal wear is still the correct maintenance approach\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eTechnical Specifications\u003c\/h2\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eModel:\u003c\/strong\u003e ALT460\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e ALT460\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air (Castair), Minnesota\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eVoltage:\u003c\/strong\u003e 460 Volt (three-phase)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eApplication:\u003c\/strong\u003e Two-compressor automatic alternation (lead\/lag control)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFormat:\u003c\/strong\u003e Relay only (no enclosure included)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCompatible Accessories:\u003c\/strong\u003e HRM75 (hour meter 24-277V), HRM50 (hour meter for gas engines), TD100 (time delay 18-240V, 1-1023 seconds), 6304 (low oil control), 6304B (float switch for low oil)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $398.86\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDimensions\/Weight:\u003c\/strong\u003e Contact us to confirm shipping dimensions\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch2\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h2\u003e\n\u003cp\u003eAir Compressor Factory Direct has specialized in compressed air systems and components since 2016. We carry the full Castair control accessory line — alternator relays, hour meters, time delays, low oil controls — and we understand how these components work together in a real duplex compressor installation. The voltage question (230V vs. 460V) and the format question (relay-only vs. mounted) come up on nearly every alternator relay order, and we can help you confirm the right answer for your specific system before anything ships.\u003c\/p\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFree Shipping:\u003c\/strong\u003e On qualifying orders — confirm at checkout or by phone\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFree Technical Support:\u003c\/strong\u003e Call 866-217-0063 before or after purchase with installation and specification questions\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFull Manufacturer Warranty:\u003c\/strong\u003e Castair components covered under manufacturer warranty — we handle warranty issues directly\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eHonest Guidance:\u003c\/strong\u003e We will tell you if a different model is the better fit for your installation before you order, not after\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSpecialist Focus:\u003c\/strong\u003e Compressed air systems and components are our focus — not a sideline. Castair controls are a core part of our inventory and we know the product line well.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003eCall 866-217-0063 for quick answers and help!\u003c\/strong\u003e\u003c\/p\u003e","brand":"Cast Air","offers":[{"title":"Default Title","offer_id":53342513922261,"sku":"ALT460","price":735.56,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/HOUR-METER_3457d9fb-83f0-411a-a628-4abc1674cae7.jpg?v=1772652569","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-automatic-two-compressor-alternator-relay-460-volt-alt460","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}