Running a 3-Phase Chain Hoist on Single-Phase Supply via VFD

Overview

Vintage chain hoists in the 1/8-ton (250 lb / 113 kg) class — including the Yale King midget and its contemporaries — were almost universally wound for three-phase supply. The pendant switch is a four-contact capacitor-start/capacitor-run design with the motor start capacitor housed beneath the pendant junction box, and the motor itself is a three-phase induction unit rated for 208-230/460 V at 50 or 60 Hz. When one of these hoists ends up in a single-phase machine shop, garage, or small fabrication facility, the usual answers are: rent or build a rotary phase converter (RPC), rewind the motor, or replace the hoist outright. A more compact and lower-cost solution is to use a small VFD rated for single-phase input and three-phase output, configured as both the phase converter and the motor controller.

This application note documents a working field implementation that powers a vintage Yale King chain hoist from a 240 V single-phase shop feeder using a Leeson SM2-series VFD. The same parameter philosophy and wiring pattern applies to Yaskawa V1000/GA500, Allen-Bradley PowerFlex 4/4M/40, Mitsubishi D700/E700, Siemens SINAMICS V20, Danfoss VLT Micro FC-051, Lenze SMVector/i500, and Hitachi WJ200 drives — the parameter numbers differ, but the control intent is identical across all of them.

Hoist Nameplate and Motor Characteristics

Before sizing the drive, confirm the following on the motor nameplate:

• Motor voltage (typically 208-230/460 V, three-phase)
• Full-load amperage (FLA) at the supply voltage you intend to feed
• Service factor (SF, usually 1.0 or 1.15 on these older units)
• Frequency (50 or 60 Hz)
• RPM (commonly 1725 at 60 Hz, 1425 at 50 Hz)
• Insulation class (typically B or F)
• Capacitor value if the pendant switch is capacitor-start/capacitor-run

For a 1/8-ton Yale King on 230 V three-phase, expect FLA in the 1.5-2.5 A range. This is well within the rating envelope of the smallest micro-VFDs on the market. Verify with a clamp meter on each output phase after first energizing from the drive, because a weak capacitor on a 4-contact pendant unit will pull one phase disproportionately and drive the VFD into current limit at start.

Drive Sizing for Single-Phase Input

A VFD fed from a single-phase supply has to handle roughly 1.5x the input RMS current it would on a three-phase feeder of the same voltage, because the full three-phase apparent power must be drawn through two input lines instead of three. Most manufacturers publish explicit single-phase ratings in the drive manual, and the rule of thumb is to oversize the drive by at least one frame.

Three-phase apparent power: kVA = √3 × V_LL × I_line / 1000. Single-phase apparent power: kVA = V × I / 1000. A 1/8-ton Yale King drawing 2.0 A at 230 V three-phase consumes √3 × 230 × 2.0 / 1000 = 0.80 kVA. On a single-phase 240 V feeder this becomes 240 × 3.46 / 1000 = 0.83 kVA — the same magnitude, drawn through two wires. Plan breaker and wire sizing for the higher single-phase line current.

Derating Math for Single-Phase Input

When a three-phase-output VFD is fed from a single-phase supply, the input rectifier stage sees roughly 1.5x to 1.73x the per-line current it would on a three-phase feeder. The output stage is unaffected, but the input section — bus capacitors, common-mode chokes, and input rectifiers — is the bottleneck. Most manufacturers derate the drive's continuous output current by the following factors when operated on single-phase input:

• 230 V class drives: 50-70% of three-phase output rating (consult the specific manual)
• 460 V class drives: 65-85% of three-phase output rating (the bus ripple is less severe at higher voltage)

For the Leeson SM2 1HP 230V drive with a published 4.0 A three-phase output rating, the single-phase output rating per the manual is 3.0 A continuous. With the 1/8-ton Yale King drawing 1.5-2.0 A under typical workshop loading (verified 200-300 lb lifts), the drive has 50% headroom — well within the safe operating envelope. Plan for thermal soak: if the drive heatsink climbs above 70 °C during a 5-minute loaded cycle, the drive is undersized for the duty cycle or has insufficient panel ventilation.

Parameter Configuration

Below is the condensed parameter set, expressed in generic terms that map cleanly to the major drive families. The Leeson SM2 example is shown as a reference; the parameter number will be different on Yaskawa, AB, Mitsubishi, etc., but the control intent is identical across all of them.

Wiring and 24 VDC Control

For a simple two-direction hoist, no external 24 VDC power supply is required. The drive's internal +24 VDC terminal (often labeled +V, +24, or PSC) sources the wetting voltage for the digital inputs, and the pendant switch contacts return to the common terminal. The internal 24 VDC rail on most micro-VFDs is rated for 50-100 mA, which is more than enough to source two digital inputs.

Commissioning Procedure

1. Verify the motor nameplate voltage matches the drive's output rating. If the motor is 230 V three-phase and the drive is a 230 V class, you can connect directly. If the motor is 460 V three-phase, use a 460 V class drive or step up.
2. Wire input L1 and L2 to the shop feeder; leave L3 disconnected. Wire output T1, T2, T3 to the hoist motor terminals U, V, W.
3. Configure the drive parameters per the parameter table above before applying the run command.
4. With the pendant in the neutral (off) position, apply feeder power. Wait the precharge time (usually 2-3 seconds) and verify the drive shows "Ready" or "Run Enable" with no fault indication.
5. Briefly command forward (hoist up) with no load on the hook. Confirm the chain lifts and the direction matches the pendant legend. If it goes the wrong way, swap any two of T1/T2/T3 on the drive output.
6. Command reverse (lower) with no load. Confirm the chain lowers and the mechanical brake (if equipped) releases cleanly.
7. Test stop: release the pendant and confirm the chain halts in coast, with no audible creep or slow descent.
8. Load test: hang a test load (start at 50% of nameplate, then climb to rated capacity) and command lift. Watch the drive current display — it should peak below the nameplate FLA and stabilize at 60-80% of FLA at full speed. If the drive trips on OC (overcurrent) during the lift, increase acceleration time or raise the minimum frequency.
9. Thermal soak: run a 5-minute loaded cycle, then check the drive heatsink temperature with an IR thermometer. The heatsink should stabilize below 70 °C. If it climbs higher, the drive is undersized for the duty cycle or has insufficient panel ventilation.
10. Inching test: command short bursts of forward motion with a 200 lb load. The drive should accelerate the load in under 1 second and coast to a stop cleanly when the pendant is released. If the chain slams to a stop, the drive is in decel mode and the stop method must be changed to Coast.

Control State Machine

Why the Minimum Frequency Matters Under Load

At very low output frequencies the VFD's V/Hz ratio is at its lowest, which means the air-gap flux in the motor is at its weakest. A loaded chain presents a high static friction at start; if the drive tries to develop torque at 0.5 Hz with a low V/Hz ratio, the motor will simply stall while drawing locked-rotor current. The drive will eventually fault on OC. Raising the minimum frequency to 1.5-3.0 Hz immediately shifts the V/Hz ratio upward and delivers substantially more current at the start of the ramp, breaking the static friction and accelerating the load cleanly.

The trade-off is reduced low-speed finesse. If the hoist is being used for fine alignment work — placing a heavy casting on a machine table, for example — the operator will notice that the chain will not creep as slowly. For most lifting applications this is a worthwhile trade because a stalled drive is useless. If precise inching is required, use a VFD with a "preset speed" function and configure the pendant's fast/slow toggle (if equipped) to call up two different speed references. On drives without preset speed, the only practical alternative is to command very brief forward bursts and release — typically the operator pulses the pendant for 200-500 ms at a time.

Cross-Reference: VFD Brand Parameter Mapping

While the parameter numbers differ across manufacturers, the control intent is the same. The following table maps the critical hoist parameters to the four most commonly encountered micro-VFD families in North American machine shops. Always confirm the exact parameter number against the drive's manual revision — the Yaskawa V1000, for example, has been through multiple firmware revisions, and the parameter numbers in the table reflect the typical 60 Hz, 230 V single-phase input configuration.

For a complete parameter list with cross-references, the official drive manuals should be downloaded and cross-checked:

• Yaskawa V1000 product page and downloads
• Allen-Bradley PowerFlex 4/4M/40 product page
• Mitsubishi D700 product page
• Lenze SMVector product page

Brand Selection Notes from the Field

Several VFD families are widely used in this duty. The following observations come from field experience across multiple brands and reflect practical usability rather than published specifications.

• Yaskawa V1000 / GA500 / HV600: Often preferred for hoist applications because the LCD keypad with English-language parameter descriptions and contextual help makes commissioning faster than drives that use a 7-segment LED display. The parameter set is comprehensive and the drive handles low-speed torque well. Excellent documentation and global technical support make this the most common recommendation for first-time VFD users.
• Allen-Bradley PowerFlex 4 and 4M: Familiar to most North American industrial electricians. The parameter structure is well-organized but the LED-only display requires the manual in hand during commissioning. Suitable for hoist duty when the user already has RSLogix 500 / Connected Components Workbench familiarity.
• Mitsubishi D700 / E700: Solid hardware and reasonable commissioning. Parameter naming differs from the AB/Yaskawa convention, so a first-time user should read the manual carefully. The FR-Configurator software allows offline parameter editing which speeds up commissioning for users who know the parameter set.
• Hitachi WJ200 / SJ700: Functional, but parameter labels and units sometimes differ from the Yaskawa/AB convention, which adds commissioning time. The ProDriveSmart commissioning tool helps.
• Siemens SINAMICS V20: Well-supported single-phase input at competitive price. Good choice for hoist duty in the 0.5-3 HP range. The BOP (Basic Operator Panel) is functional but the optional SINAMICS V20 BOP Interface is recommended for faster commissioning.
• Danfoss VLT Micro FC-051: Compact, single-phase input supported, but the parameter set is less intuitive than Yaskawa or AB for first-time users. The MCT 10 setup software is recommended for parameter management.
• Lenze SMVector / i500: European heritage; parameter structure is clean and the SMVector in particular is available in IP65/NEMA 4 enclosures for shop-floor environments. The i500 is the newer platform with better single-phase support.
• Leeson SM2: Budget-priced and functionally adequate. The LED display and parameter labels are functional but not as polished as Yaskawa. This is the example used in this article because of price; the same parameter intent applies across the other families.

Troubleshooting Matrix

Safety Considerations

Working around an electric chain hoist presents specific hazards that the VFD conversion does not eliminate:

• The motor in a vintage Yale King may not have an internal brake — the chain hoist's mechanical brake assembly holds the load. Verify the brake is functional before lifting anything over personnel.
• Capacitors inside the pendant switch housing store charge. Discharge the capacitor bank through a 10 kΩ resistor before working on the pendant wiring.
• A stalled drive on a lifting load is dangerous. If the drive trips on OC mid-lift, the load will fall unless the mechanical brake is functional. Test the mechanical brake independently before trusting the VFD-controlled hoist with a person below.
• Single-phase input feeders are typically protected by a 1-pole or 2-pole breaker. Verify the drive's input amperage is below 80% of the breaker rating per NEC 210.20(A) and 240.4(D).
• Use a drive with a UL 508C listing (or equivalent IEC 61800-5-1) for industrial control panel installations. The Yaskawa V1000, AB PowerFlex, and Mitsubishi D700 all carry these listings.
• Maintain a clear path for the load to fall in the event of a brake failure. Do not stand under a suspended load during testing.

Verification Checklist

After commissioning, the following should be verified before the hoist is put into production service:

• Direction matches the pendant legend (Up = lift, Down = lower)
• Stop is true coast — no creep after pendant released
• Drive heatsink stabilizes below 70 °C during a 5-minute loaded cycle
• Drive current stays below nameplate FLA at full load, full speed
• Mechanical brake holds the load with the drive disabled (test by cutting drive input power mid-lift on a controlled test load)
• Pendant contacts are normally open; no shorted or stuck contacts
• Capacitor on the pendant housing is within ±10% of nameplate capacitance
• All drive parameters recorded and saved to a keypad EEPROM or backed up to a file
• Enclosure has appropriate ventilation; ambient temperature below 40 °C
• Input feeder is protected by a breaker sized at 125% of drive input FLA per NEC 430.52

FAQ