JY Single Phase AC Gear Motor | Capacitor Start Induction Motor

Product Overview

Not every installation has access to three-phase power. Small workshops, rural agricultural facilities, residential-adjacent commercial buildings, and portable equipment often rely on a standard 220 V single-phase supply. The JY series capacitor-start single phase induction motor is purpose-built for exactly this situation: it delivers high starting torque from a single-phase line, making it the natural drive choice for loads that resist initial rotation — reciprocating compressors, hermetic refrigeration compressors, positive-displacement pumps, and medical apparatus with heavy mechanical seals.

The product line spans three frame sizes — 09, 1, and 2 — covering output ratings from 0.18 kW (0.25 HP) through 2.2 kW (3 HP) at 2-pole and 4-pole speed configurations. Buyers can choose between cast iron and die-cast aluminum housings, depending on whether weight savings or ruggedness takes priority. The starting capacitor is mounted in a ventilated housing on top of the motor, which keeps it accessible for inspection and simplifies replacement if the capacitor ever fails. All JY motors feature a totally enclosed, fan-cooled (TEFC) construction with protection ratings of IP44 or IP54. For Korean buyers seeking a cost-effective replacement of single-phase AC gear motor drives currently sourced from higher-priced suppliers, the JY series offers equivalent torque performance at a fraction of the landed cost.

Technical Specifications

Operating Conditions

The JY series is rated for the following service conditions. Motors destined for environments outside these parameters should be discussed with our engineering team for appropriate derating or modifications.

Performance Data

The table below lists the complete JY model range with output power, rated current, power factor, efficiency, speed, and starting torque ratios. All values are measured at 220 V / 50 Hz.

Type	Output		Voltage	Frequency.	Current	Power	Eff	Speed	Tstart/Tn	Ist/In	Tmax/Tn
	KW	HP	(V)	(Hz)	(A)	factor	(%)	(r/min)
JY09B-2	0.18KW	0.25HP	220	50	2.15	0.76	50	2800	3	6.5	1.8
JY09A-2	0.25KW	0.34HP	220	50	2.82	0.76	53	2800	3	6.5	1.8
JY1B-2	0.37KW	0.5HP	220	50	3.74	0.75	60	2800	3	6.5	1.8
JY1A-2	0.55KW	0.75HP	220	50	5.36	0.74	63	2800	3	7	1.8
JY2B-2	0.75KW	1HP	220	50	6.81	0.77	65	2800	2.8	7	1.8
JY2A-2	1.1KW	1.5HP	220	50	9.45	0.79	67	2800	2.8	7	1.8
JY09B-4	0.12KW	0.16HP	220	50	1.7	0.63	48	1400	2.8	7	1.8
JY09A-4	0.18KW	0.25HP	220	50	2.52	0.65	50	1400	2.8	6.5	1.8
JY1B-4	0.25KW	0.34HP	220	50	3.2	0.67	53	1400	2.8	6.5	1.8
JY1A-4	0.37KW	0.5HP	220	50	4.03	0.72	58	1400	2.8	7	1.8
JY2B-4	0.55KW	0.75HP	220	50	5.12	0.74	66	1400	2.8	7	1.8
JY2A-4	0.75KW	1HP	220	50	6.9	0.76	68	1400	2.8	7	1.8

JY Series Capacitor Start Single Phase Induction Motor Mounting Arrangements:

Conventional mounting type and suitable frame size :

Frame	Basic Type			DerivedType
	V3	V5	V6	B6	B7	B8	V15	V36	B14	B34	V18
63~112	√	√	√	√	√	√	√	√	√	√	√
132~160	√	√	√	√	√	√	√	√	-	-	-
180~280	-	-	-	-	-	-	-	-	-	-	-
315~355	-	√	-	-	-	-	-	-	-	-	-

Note "√" indicates the structure type that can be manufactured

JY Series Capacitor Start Single Phase Induction Motor Installation Dimension:

How the Capacitor-Start Motor Works

The Single-Phase Starting Problem

A single-phase supply produces only a pulsating magnetic field inside the stator — it alternates back and forth along one axis rather than rotating around the air gap the way a three phase motor field does. According to double-revolving-field theory, this pulsating field can be decomposed into two equal but opposite rotating components. At standstill, these two components produce equal and opposite torques, so the net starting torque is zero. The rotor will not begin spinning on its own. Every practical single-phase motor therefore needs an auxiliary mechanism to break this symmetry at startup and produce a net torque in one direction.

Capacitor-Start Solution

The JY motor addresses the starting problem with a dedicated start winding that is physically displaced from the main (run) winding by approximately 90 electrical degrees around the stator bore. A high-capacitance electrolytic capacitor is connected in series with this start winding. The capacitor shifts the current in the start winding ahead of the current in the run winding, creating a phase difference that simulates a two-phase rotating field. This artificial rotating field produces enough torque to accelerate the rotor from rest to roughly 75 % of synchronous speed. At that point, a centrifugal switch mounted on the rotor shaft disconnects the start winding and its capacitor from the circuit, and the motor continues to run on the main winding alone.

The starting torque ratio (Tstart/Tn) of the JY series reaches 2.5 to 3.0 times rated torque, which is substantially higher than what a shaded-pole or permanent-split-capacitor motor can deliver. This high breakaway torque is the reason the JY is specified for compressors and refrigeration units that must overcome significant back-pressure when restarting after a brief power interruption.

Typical Application Scenarios

Air Compressors

Reciprocating piston compressors used in small automotive repair shops, dental clinics, and pneumatic tool stations demand a motor that can push the piston past top-dead-center against full cylinder pressure during startup. The JY series starting torque of 3× rated torque handles this requirement. A JY2A-2 rated at 0.75 kW is a common match for portable compressors in the 25 to 50 liter tank range.

Refrigeration and Cold Storage

Walk-in coolers, display-case compressor racks, and ice-making machines often run on single-phase 220 V circuits in small commercial settings. The hermetic or semi-hermetic compressors inside these units need a motor that starts reliably even when refrigerant head pressure is still elevated after a defrost cycle. The JY motor is specified for this exact duty, and its Class B/F insulation handles the ambient heat near condenser coils without premature degradation.

Medical and Laboratory Equipment

Vacuum pumps in operating rooms, centrifuges in clinical labs, and sterilizer blowers all require consistent starting performance and low vibration. Hospitals and clinics typically have single-phase power outlets at each station, making a three-phase motor impractical without a dedicated converter. The JY fills this gap with a quiet, vibration-controlled package that nurses and technicians can operate without concern about excessive noise in sensitive care areas.

Small Agricultural Machinery

Feed grinders, grain cleaners, and irrigation pumps on small Korean farms often connect to residential-grade single-phase wiring. The 4-pole (1400 r/min) JY models provide ample torque for belt-driven grain processing at moderate speeds, while the 2-pole (2800 r/min) variants suit centrifugal water pumps that need higher shaft speed. The cast-iron frame option is preferred for farm environments where the motor may be exposed to dust, grain chaff, and occasional hose-down cleaning. Browse additional types of gear motor suited for agricultural duty in our product catalog.

Installation and Maintenance Guide

Pre-Installation Checks

Before mounting, confirm the supply voltage at the outlet under load — it should stay within 220 V ± 10 %. A voltage sag beyond this range during motor starting can prevent the rotor from reaching the centrifugal-switch trip speed, leaving the start winding energized and causing it to overheat within seconds. Also verify that the circuit breaker or fuse is rated for the starting current (Ist) listed in the specification table, which can be 6 to 6.5 times the motor rated current.

Mounting and Alignment

Bolt the motor to a rigid, flat base using all four foot-mounting holes. Use a dial indicator or laser alignment tool to bring the motor shaft and driven shaft within 0.05 mm total indicated runout at the coupling faces. Misalignment beyond this limit accelerates bearing wear and can excite torsional vibration in the coupling. For belt-driven arrangements, set belt tension according to the belt manufacturer's deflection chart and check tension again after the first 48 hours of operation, since new belts stretch slightly.

Ongoing Maintenance Schedule

Keeping the JY motor in reliable service requires only a few periodic tasks:

• Every 500 hours: Listen for unusual bearing noise during startup. A grinding or whining sound indicates bearing degradation — schedule a replacement before a seizure occurs.
• Every 2 000 hours: Clean the external fan cover and air intake openings. In dusty environments (grain mills, woodworking shops), reduce this interval to 500 hours.
• Every 5 000 hours: Inspect the centrifugal switch contacts for pitting or carbon buildup. Worn contacts may fail to disengage the start winding, causing a rapid temperature rise. Replace the switch assembly if contact surfaces show visible erosion.
• Every 8 000 hours or annually: Check the starting capacitor with a capacitance meter. If the measured value has dropped more than 10 % below the stamped rating, replace the capacitor. A weak capacitor reduces starting torque and can prevent the motor from reaching operating speed under heavy load.
• Every 10 000 hours: Perform an insulation resistance test (megger test) between windings and frame. A reading below 5 MΩ at 500 V DC suggests moisture ingress or insulation deterioration — investigate and address before returning the motor to service.

Energy Efficiency Considerations for Single Phase Motors

Single-phase motors inherently operate at lower efficiency and power factor than their three-phase counterparts of the same rating. This is a physical consequence of carrying all the load current through a single supply conductor and running with a pulsating (rather than smoothly rotating) magnetic field. The JY series efficiency ranges from 50 % on the smallest 0.18 kW frame up to roughly 65 % on the larger 0.75 kW models, with power factors between 0.62 and 0.79.

While these numbers are lower than what a modern IE3-class three phase motor achieves, they are typical — and often the best available — within the capacitor-start single-phase category. The key to minimizing energy waste lies in correct sizing: an oversized motor running at partial load operates further from its optimal efficiency point. If your application consistently draws less than 50 % of the motor rated power, step down to a smaller frame. A 0.37 kW motor loaded to 80 % will consume noticeably less electricity per year than a 0.75 kW motor loaded to only 40 %.

For installations where energy cost is a top concern and three-phase power can be made available (via a phase converter or utility upgrade), switching to a three-phase ac motors setup paired with a VFD offers measurable savings. Our sales team can calculate the payback period for your specific operating hours and electricity rate. In many Korean commercial buildings, the investment pays for itself within 18 months through lower utility bills alone.

Why Choose Korea Ever-Power

Korea Ever-Power PTO Shaft Co., Ltd has served the Korean industrial market for years, supplying motors, gearboxes, and power transmission components to factories across the peninsula. Here are the practical reasons our customers keep reordering:

• Factory-direct pricing with no middleman markup — the same motor that distributors mark up 40 % or more reaches you at manufacturer cost plus a fair margin.
• Local spare-parts warehouse in Korea stocking bearings, capacitors, fan covers, and terminal blocks for all major motor series.
• Single-unit orders accepted — no minimum quantity requirement for standard catalog models.
• OEM customization including special shaft lengths, non-standard voltages (110 V, 200 V, 240 V), custom paint colors, and private-label nameplates.
• Engineering support in Korean and English — motor selection, dimensional verification, and VFD pairing guidance provided free of charge.
• ISO 9001 and CE certified production facility with documented traceability from raw material to finished product.
• Typical lead time of 7 to 15 working days from order confirmation to delivery at your Korean address.

Related and Complementary Products

Single-phase motors are often just one component in a larger mechanical system. Depending on the driven equipment, you may also need a speed reducer, a coupling, or a chain-and-sprocket kit to complete the installation.

For applications where the motor output speed is too high for the driven load — common on grain mills, dough mixers, and slow-running conveyor belts — a planetary gearbox or a right-angle worm gear reducer brings the shaft speed down to the required range while multiplying torque. If the motor and load shafts are not coaxial, a roller chain and sprocket set provides a flexible and affordable power transmission path. Our full range of gear motor options and drive components is available for review on the ac gear motor product page.

Frequently Asked Questions

What happens if the centrifugal switch fails to open during operation?
The start winding will remain energized, drawing excessive current and generating heat rapidly. Most JY motors include a thermal protector (bi-metal cutout) that trips within a few seconds to prevent winding damage. If the motor shuts down unexpectedly after reaching speed, a stuck centrifugal switch is a common cause — inspect and replace the switch assembly.

Can I reverse the rotation direction of the JY motor?
Yes. Swap the two leads of the start winding at the terminal block. The motor nameplate or the wiring diagram inside the terminal cover identifies the start winding terminals. Do not swap the main winding leads, as this has no effect on rotation direction on a capacitor-start design.

Is the JY motor suitable for use with a single-phase VFD?
Capacitor-start motors are not designed for inverter duty. The centrifugal switch and external capacitor interfere with the VFD output waveform, and the start winding circuit can be damaged by the high-frequency PWM pulses. If you need variable speed on a single-phase supply, use a single-phase input VFD paired with a three-phase motor from our YS or YE2 range.

What is the noise level of the JY series at full load?
Measured at 1 meter from the motor surface, airborne noise is typically between 55 dB(A) for the smallest frame and 68 dB(A) for the largest. The centrifugal switch produces a brief click at startup, which is normal. If a persistent rattling sound develops, inspect the fan and fan cover for contact.

Can I get the JY motor with a 110 V winding for export to other markets?
Yes. Custom voltage windings including 110 V, 120 V, 200 V, and 240 V are available on request. Specify the target voltage and frequency (50 Hz or 60 Hz) at the time of ordering. Custom-wound units add approximately 5 working days to the standard lead time.

How do I choose between the cast-iron and aluminum housing options?
Choose cast iron when the motor will be mounted in a harsh environment with physical impact risks, heavy vibration from adjacent equipment, or exposure to corrosive chemicals that attack aluminum. Choose the aluminum housing when weight reduction is important or when the motor is installed in a clean, indoor setting where the better thermal conductivity of aluminum provides a cooling advantage.

What is the expected service life of the starting capacitor?
Under normal operating conditions (fewer than 10 starts per hour, ambient temperature below 40 °C), an electrolytic start capacitor lasts approximately 5 to 7 years. Frequent cycling, high ambient heat, or voltage surges shorten this life. Keeping a spare capacitor in stock is recommended for equipment that runs in a production-critical role.

Does the JY motor come with mounting hardware included?
The motor ships with the terminal box, fan cover, and nameplate attached. Foot-mounting bolts, alignment shims, and couplings are not included, as these depend on your specific machine base configuration. We can supply standard metric bolt sets as an add-on if requested.

Customer Reviews

Kwon Na-young, Equipment Manager, Jeju (early 2025)
"We put a JY1A-2 on a small air compressor at our vehicle service center. Starts up strong every time, even first thing on a cold January morning. The cast-iron frame handles getting bumped by tool carts without any dents. Very practical motor."

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Hwang Jun-seo, Facility Engineer, Daejeon (mid 2024)
"Needed a single phase motor for a vacuum pump in our laboratory. The JY09A-2 was the right size and the price was fair. It has been running daily for about eight months now, no problems with the centrifugal switch or the capacitor. Quieter than I expected for a motor this type."

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Ahn Dae-ho, Production Supervisor, Gyeongsang-do (late 2024)
"We ordered five JY2A-2 motors for our grain cleaning workshop. Three-phase power is not available at that location. The motors handle the load without overheating even during the summer harvest season when they run 14 hours a day. Delivery was on time — 11 days from order to our warehouse."

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Song Hye-jin, Clinic Administrator, Seoul (early 2025)
"Our dental compressor needed a motor replacement. The original was an imported brand that the local distributor quoted at nearly three times the price of this JY unit. We made the switch, and the compressor runs the same as before. The noise level is acceptable for a clinical environment. Saved us a significant amount on a straightforward replacement."

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Park Soo-hyun, Farm Owner, Chungcheong-do (mid 2025)
"I run a small mushroom cultivation greenhouse. The 0.37 kW motor drives a circulation fan that keeps air moving through the grow room. Single-phase 220V is all we have on the property. The motor starts reliably even during the monsoon season when voltage tends to drop. I bought the aluminum frame version and it weighs almost nothing. Good purchase."

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Jeon Min-ji, Maintenance Technician, Incheon (late 2024)
"Replaced a no-name motor on a refrigeration unit at our cold storage facility. The JY1B-2 dropped right in — same shaft height, same mounting bolt spacing. The thermal protector tripped once during a voltage brownout, which actually saved the motor from damage. Good safety feature."

Packing and Shipping