{"product_id":"castair-open-drip-proof-motor-25-hp-208-230-460v-3ph-frame-284t-rpm-1725","title":"Castair Open Drip Proof Motor 25 HP 208\/230\/460V 3Ph. Frame 284T RPM 1725","description":"\u003ch2\u003eCastair Open Drip Proof Motor — 25 HP, 208\/230\/460V, 3-Phase, Frame 284T, 1725 RPM\u003c\/h2\u003e\n\u003cp\u003eThe Castair 25-284-3 is a 25 HP, three-phase, 1725 RPM replacement motor for large-capacity Castair belt-drive air compressors. The NEMA 284T frame and 1725 RPM speed are the standard specifications for heavy-duty industrial compressor drive motors in the 20-30 HP range. At $2,360.74, this is a major component purchase — the kind of replacement that happens when the original motor fails after years of service or when upgrading a compressor to higher output capacity.\u003c\/p\u003e\n\u003cp\u003eThe three-voltage rating (208\/230\/460V) is practical for industrial installations. Many shops and facilities run 460V three-phase power for large motor loads to reduce current draw and wire size requirements. The same motor handles all three voltages through wiring configuration changes — no hardware change required. Confirm your available voltage before ordering and verify the motor nameplate wiring diagram at installation.\u003c\/p\u003e\n\u003ch3\u003eMotor Specifications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e 25-284-3\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHorsepower:\u003c\/strong\u003e 25 HP\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVoltage:\u003c\/strong\u003e 208\/230\/460V (three-voltage, field-configurable)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePhase:\u003c\/strong\u003e Three-phase (3Ph)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFrame:\u003c\/strong\u003e NEMA 284T\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRPM:\u003c\/strong\u003e 1725 (standard four-pole three-phase speed)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEnclosure:\u003c\/strong\u003e Open Drip Proof (ODP)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air (Castair)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePrice:\u003c\/strong\u003e $2,360.74\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eNEMA 284T Frame — What It Means for Your Installation\u003c\/h3\u003e\n\u003cp\u003eThe NEMA 284T is a large frame in the NEMA T-frame series. The 284 defines the physical dimensions: 7\" shaft centerline height, specific bolt hole spacing, and a standard shaft size for this HP class. The T suffix indicates a NEMA standard shaft extension length suitable for belt-drive and coupling applications.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eShaft centerline height:\u003c\/strong\u003e 7 inches (NEMA 284 standard)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFrame footprint:\u003c\/strong\u003e Standardized NEMA dimensions — a 284T replacement should mount on any Castair mount designed for 284T frame motors\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eShaft diameter:\u003c\/strong\u003e Standard NEMA 284T — confirm against your existing sheave bore if reusing the existing drive sheave\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eBase mounting:\u003c\/strong\u003e Rigid base — pairs with the Castair 284D adjustable belt tensioner base for this motor size\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e1725 RPM — Low-Speed for Large Pump Drives\u003c\/h3\u003e\n\u003cp\u003eUnlike the 3450 RPM motors used on smaller compressors, large 25 HP belt-drive units use 1725 RPM motors. The slower shaft speed is matched to larger pump displacement through sheave sizing to achieve the correct pump RPM for the designed CFM output. Do not substitute a 3450 RPM motor in a 1725 RPM application — the pump will run at twice the designed speed and will fail quickly.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eStandard for large compressors:\u003c\/strong\u003e 1725 RPM (four-pole) is the correct speed class for 15 HP and above compressor motors in most configurations\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSheave sizing matters:\u003c\/strong\u003e The motor-to-pump drive ratio is set by the sheave diameter combination — the motor RPM feeds into that calculation. If replacing from 3450 RPM, the sheave ratio must change\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eThree-Phase Power — What You Need for Installation\u003c\/h3\u003e\n\u003cp\u003eThis motor requires a three-phase power supply. Single-phase power at any voltage will not work. Confirm your shop has three-phase service before ordering a 25 HP three-phase motor — running a motor of this size on a single-phase supply via a phase converter is possible but consult an electrician for the specifics of your installation.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e208V 3-phase:\u003c\/strong\u003e Common in commercial buildings and industrial facilities with older 208V service\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e230V 3-phase:\u003c\/strong\u003e Standard U.S. industrial voltage for motors in this HP class\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e460V 3-phase:\u003c\/strong\u003e Reduces current draw by half compared to 230V — the preferred wiring configuration for facilities with 480V service to minimize wire sizing and disconnect ratings\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCompanion Parts — Belt Tensioner and Drive Components\u003c\/h3\u003e\n\u003cp\u003eA 25 HP motor at 284T frame uses these companion Castair parts:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e284D ($203.28):\u003c\/strong\u003e Adjustable belt tensioner base for 25 and 30 HP motors — the mount that allows belt tension adjustment on this motor size\u003c\/li\u003e\n\u003cli\u003eDrive sheaves and belts appropriate for the pump-to-motor RPM ratio your application requires\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eWhen Does a Shop Need a 25 HP Replacement Motor?\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMotor failure on an existing large-capacity Castair compressor:\u003c\/strong\u003e When a 25 HP motor fails, the 25-284-3 is the OEM replacement spec for Castair units using this frame and speed combination\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eUpgrading a 20 HP installation to 25 HP:\u003c\/strong\u003e Moving up in HP on the same 284T frame is a common upgrade path when shop air demand has grown. Verify the pump and drive components are rated for the higher HP\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eRebuilding a used large compressor:\u003c\/strong\u003e Castair pumps for the 20-30 HP range are paired with 284T frame motors — the 25-284-3 is a common spec for this class\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003ePart Number:\u003c\/strong\u003e 25-284-3\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eManufacturer:\u003c\/strong\u003e Cast Air (Castair)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHorsepower:\u003c\/strong\u003e 25 HP\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eVoltage:\u003c\/strong\u003e 208\/230\/460V (three-phase, field-configurable)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePhase:\u003c\/strong\u003e 3 Phase\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFrame:\u003c\/strong\u003e NEMA 284T\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eSpeed:\u003c\/strong\u003e 1725 RPM\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eEnclosure:\u003c\/strong\u003e Open Drip Proof (ODP)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eList Price:\u003c\/strong\u003e $2,360.74\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e\u003cem\u003eNote: Manufacturer product page data was not available at time of writing. Specifications are derived from the product name and part number. Contact us to confirm fit for your specific Castair compressor model before ordering.\u003c\/em\u003e\u003c\/p\u003e\n\u003ch3\u003eWhy Buy From Air Compressor Factory Direct?\u003c\/h3\u003e\n\u003cp\u003eWe have specialized in industrial air compressor equipment since 2016. A 25 HP motor is not a part you want to order without confirming fit. Call us with your Castair compressor model number — we will confirm the correct motor specification, verify the frame and speed are right for your pump, and advise on companion drive components if needed.\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree shipping\u003c\/strong\u003e on qualifying orders (freight for motors of this size)\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFree tech support:\u003c\/strong\u003e Call 866-217-0063 to confirm fit before ordering\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFull manufacturer warranty\u003c\/strong\u003e on all motors\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eHonest guidance:\u003c\/strong\u003e We will tell you if this motor specification does not match your application\u003c\/li\u003e\n\u003c\/ul\u003e\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":53342503633109,"sku":"25-284-3","price":4353.72,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0622\/8466\/0949\/files\/motors.jpg?v=1772652473","url":"https:\/\/aircompressorfactorydirect.com\/products\/castair-open-drip-proof-motor-25-hp-208-230-460v-3ph-frame-284t-rpm-1725","provider":"Air Compressor Factory Direct","version":"1.0","type":"link"}