380V Conical Rotor Motor Wiring Diagram & Forward-Reverse Guide
Electric hoist motor wiring uses a conical-rotor three-phase asynchronous motor rated at 380V/50Hz. The connection mode is either Y-type (star connection, applicable to 1.5–7.5kW small motors) or Δ-type (delta connection, applicable to 5.5–15kW larger motors). Forward and reverse rotation is achieved by swapping any two phases via contactors KM1/KM2. The thermal overload relay FR is set to a trip current of 1.05–1.1 times the motor's rated current. The brake rectifier module converts AC 380V input to DC 99V output, energizing the brake to release it; when the motor is de-energized, braking is completed within 0.2 seconds.
The conical-rotor brake motor is the core drive component of an electric hoist. Its unique feature is that the conical rotor at the motor's rear generates an axial magnetic pull when energized, compressing the brake spring to release the brake. When power is cut, the spring returns, pressing the rotor's braking face against the brake ring to create friction and stop the motor—no external brake is required. This integrated braking design means the electric hoist motor wiring includes additional brake rectifier and control circuits compared to a standard asynchronous motor. The following sections explain the wiring method and troubleshooting for electric hoist motors in accordance with FEM 1.001, IEC 60204-32, and IEC 60947-4-1 standards.
1. Three-Phase Motor Y/Δ Wiring Methods
The junction box of an electric hoist motor typically contains six terminal blocks labeled U1, V1, W1 (start ends) and W2, U2, V2 (finish ends). Choose the Y-type or Δ-type connection based on the rated voltage and connection designation shown on the motor nameplate.
Y-type (star) connection: Short the three finish ends W2, U2, V2 together to form the neutral point, and connect U1, V1, W1 to the three-phase power supply L1, L2, L3 respectively. In the Y-type connection, each phase winding sees 220V (line voltage 380V divided by √3), making it suitable for motors rated at 380V/660V. The Y-type offers lower starting current and lower starting torque, and is commonly found in 1.5–7.5kW hoisting motors for CD1-type electric hoists. Use a shorting bar to connect the W2-U2-V2 terminals, and connect the three power cords to U1, V1, and W1. The shorting bar must be tightened securely—a loose connection can cause single-phasing and burn out the motor.
Δ-type (delta) connection: Connect U1-W2, V1-U2, and W1-V2 in pairs to form a closed delta. Connect L1 to the U1-W2 terminal, L2 to V1-U2, and L3 to W1-V2. In the delta connection, each phase winding sees the full line voltage of 380V, delivering higher output power. This configuration is suitable for larger motors rated at 5.5–15kW. Note: if the nameplate reads "380V Δ," the motor can only be wired in delta. If it reads "380V/660V Y/Δ," either star or delta is acceptable—but a star-delta starting circuit must be configured in the control cabinet.
Δ-YY two-speed motor: The MD1-type two-speed electric hoist uses a dual-winding Δ-YY structure—the fast winding is delta-connected (rated power) and the slow winding is YY-connected (approximately 1/3 to 1/4 of rated power). The two windings are switched by separate contactors, with 12 leads brought out from the junction box: 6 for the fast-speed delta terminals and 6 for the slow-speed YY terminals. When wiring a two-speed motor, an electrical interlock must be provided between the fast and slow contactors (interlock contacts wired in series with each other's coil circuits) to prevent both contactors from closing simultaneously, which would short-circuit the windings.
2. Forward and Reverse Rotation Control Wiring
Hoisting and lowering of the electric hoist are achieved by reversing the motor's direction of rotation—the load contacts of KM1 (hoisting contactor) and KM2 (lowering contactor) in the control cabinet swap any two phases to change the phase sequence. Typical configuration: when KM1 is energized, L1-U1, L2-V1, L3-W1, and the motor rotates forward (hoisting); when KM2 is energized, L1-U1, L2-W1, L3-V1 (L2 and L3 are swapped), the phase sequence changes, and the motor rotates in reverse (lowering). Both electrical interlock and mechanical interlock must be provided between KM1 and KM2 as double protection to prevent simultaneous closure, which would cause a phase-to-phase short circuit on the power supply.
3. Brake Rectifier and Brake Wiring
The conical-rotor motor incorporates a dedicated DC braking system. A rectifier module converts AC 380V to DC 99V to power the brake coil. The input side (AC side) of the brake rectifier module is connected to the motor terminals in parallel with the stator winding. When the motor is energized, the stator creates a rotating magnetic field while the brake rectifier outputs DC 99V to keep the brake released. When the motor is de-energized, the rectifier loses power simultaneously, and the brake spring presses the rotor's braking face against the brake ring to apply the brake.
Common brake faults: Excessive load drop after braking (exceeding S≤v/100, meaning at a lifting speed of 8 m/min the load drop must not exceed 80 mm)—first check that the brake air gap is within 0.5–1.5 mm; if out of tolerance, loosen the lock nut and turn the adjusting nut clockwise to reduce the air gap. Brake rectifier module burnout—often caused by overvoltage from single-phasing; measure the rectifier output with a multimeter, which should read DC 99V±5V; replace the module if out of range. Brake fails to release or releases with latency—check the brake rectifier output and the brake coil resistance (normally 200–500Ω); replace the brake assembly if the coil is shorted or open.
4. Key Motor Wiring Parameters
| Parameter Item | CD1 Type Single-Speed | MD1 Type Two-Speed | HCHeavy-duty type |
|---|---|---|---|
| rated voltage | 380V/50Hz | 380V/50Hz | 380V/50Hz |
| motor power Range | 0.8~13kW | 0.8/0.2~15/4kW | 13~42kW |
| connection mode | YorΔ(according to Nameplate) | △-YYdualwinding | YorΔ(according to Nameplate) |
| number of lead wires | 6pcs(U1~W2) | 12pcs(dualwinding) | 6pcs(U1~W2) |
| Brakingrectified output | DC 99V | DC 99V×2 | DC 99~170V |
| Brakeair gap | 0.5~1.5mm | 0.5~1.5mm | 1.0~2.5mm |
| Insulation Class | Fstage | Fstage | Fstage/Hstage |
| Protection Rating (IP) | IP44/IP54 | IP44/IP54 | IP54/IP55 |
5. Motor Wiring Data Card
| 380V rated operation Voltage three-phase380V/50HzStandard Power Supply,Δ/Y/△-YYthree connection modes according to Motor Nameplateselection | 99V Brakingrectified output Voltage AC 380Vafter half-wave rectification DC 99Vfor Motor Brakecoil,±5Vwithin normal range | 1.05~1.1 Thermal Overload Relaysetting Coefficient FRsetting current=rated current×1.05~1.1times, too small causes nuisance trip, too large loses protection |
| 0.5~1.5mm Brake Standardair gap cone rotor brakeair gapcharacteristic value, out-of-tolerance requires adjustment Lock Nutrestore | 6pcs Motornumber of lead wires Single-Speedmotor wiringbox Standard6terminal(U1/V1/W1 + W2/U2/V2), Two-Speed12terminal | 0.2s Brake Response time Motorfrom power-off to Brakefull braking time, ensureload dropbelow ISO 4301 Crane Design Standard |
The data above summarizes the core parameters for electric hoist motor wiring. Every Kelude electric hoist motor undergoes a no-load trial run, forward and reverse rotation testing, and brake slip distance inspection before delivery, ensuring correct wiring and reliable braking on every unit. For more on motor selection and configuration, refer to the contactor control circuit details in the electric hoist pendant control wiring guide.
Electric Hoist Motor Wiring — Technical Note
"The most common issue in electric hoist motor wiring isn't a reversed phase sequence — it's a loose shorting bar. In a Wye (Y) configuration, if even one screw on the W2-U2-V2 shorting bar works loose, the motor will single-phase: it hums but won't turn, and within seconds the winding temperature can spike past 120°C, rapidly degrading the insulation layer. Another frequently overlooked point: the fast and slow speed windings of an MD1 two-speed motor must be electrically interlocked. If both contactors energize simultaneously, the potential difference between the two windings creates circulating current that can burn a hole through the junction box almost instantly. At Kelude Heavy Industry, every two-speed motor control cabinet undergoes an interlock functional test before delivery — we deliberately energize both contactors at once to verify that the mechanical and electrical interlocks cut power within 5 ms."
6. Frequently Asked Questions
Q: Why does my electric hoist motor hum but not turn?
A: A humming motor that won't turn is the classic symptom of single-phasing. Troubleshooting sequence: ① Use a multimeter to check for balanced three-phase voltage at the motor junction box (U-V, V-W, and W-U should each read 380V ±10%). ② If one phase is missing, inspect fuse FU — a clean break indicates overload, while a shattered fuse points to a short circuit. ③ If voltage is balanced, check the internal motor connections — is the W2-U2-V2 shorting bar in the Wye configuration loose? (Tightening torque: 2–3 N·m). ④ If all checks pass, disconnect the motor and use a Megohmmeter (Insulation Tester) to measure phase-to-ground insulation resistance — a reading below 0.5 MΩ means the winding is burned out and the motor must be replaced. During single-phasing, the motor should be stopped within 10 seconds; otherwise, winding temperature rise can exceed 120°C.
Q: How do I reverse the motor direction? What if hoisting and lowering are swapped?
A: Reversed hoisting/lowering directions are caused by an incorrect phase sequence in the contactor secondary circuit. Here's the fix: disconnect the main power, open the electrical control cabinet, and locate the load-side wiring of the hoisting contactor (KM1) and lowering contactor (KM2). Swap any two phase wires on the KM2 output (e.g., U2 and V2) — after the swap, the phase sequence at the motor when KM2 energizes will be opposite to KM1, reversing the rotation. Important: swap the load-side wires (the ones going to the motor), not the coil-side control wires. After the swap, verify: ① Pressing the hoist button turns the motor forward (hook rises), ② Pressing the lower button turns it in reverse (hook descends), ③ The Emergency Stop Button stops the motor immediately. If both directions end up reversed after the swap, you'll also need to swap two phases at the junction box.
Q: What's the difference between Wye (Y) and Delta (Δ) motor wiring?
A: The main difference lies in the voltage each winding sees and the resulting output power. In a Wye (Y) configuration, each winding sees 220V (line voltage 380V ÷ √3), starting current is roughly 5–7 times the rated current, and starting torque is relatively low (about 1.5–2 times rated torque) — suitable for smaller motors from 1.5 to 7.5 kW. In a Delta (Δ) configuration, each winding sees the full 380V, starting current can reach 7–10 times rated current, and starting torque is higher (approximately 2–2.5 times rated torque) — suited to larger motors from 5.5 to 15 kW. Always check the motor nameplate before wiring — a "380V Δ" rating means Delta only, while "380V/660V Y/Δ" allows star-delta starting. The CD1 5t electric hoist uses a 7.5 kW hoisting motor wired in Wye (Y) from the factory.
Q: How do I wire the thermal overload protector on an electric hoist motor?
A: Thermal protection for electric hoist motors is provided by a Thermal Overload Relay (FR) wired in series with the control circuit. The FR's heating elements are connected in series with the main circuit (one per phase), and its auxiliary normally closed contact is wired in series with the contactor coil control circuit. When motor overload current exceeds 1.2 times the FR setting for a sustained period, the internal bimetal strip bends and trips the auxiliary contact, cutting power to the contactor coil and stopping the motor. The FR setting current = motor rated current × 1.05–1.1. For a 5t electric hoist hoisting motor (7.5 kW, rated current approximately 15.5 A), set the FR to 16–17 A. Choose automatic reset for Unattended Operation or manual reset (requiring an operator to confirm the fault is cleared before restarting) — manual reset is recommended.
For more on electric hoist electrical control systems, see the electric hoist remote control wiring guide for a complete wiring scheme covering the wireless Remote Receiver and motor contactors.
