Star-Delta Starting Current / Torque
Compare direct-on-line and star-delta starting line current, starting torque, and star phase voltage; check whether the load can start.
Key points
Star-Delta Starting Current / Torque: Compare direct-on-line and star-delta starting line current, starting torque, and star phase voltage; check whether the load can start. Formula: I_Y = I_Δ/3 | T_Y = T_Δ/3 | U_phase,Y = U_line/√3. Enter parameters on the DD-CAT IDE online tool page to get results instantly, with a calculation-model diagram that updates with the inputs. Star-delta starting applies only to motors designed for delta running with six accessible terminals; star duration depends on starting current and speed. Star starting torque is only one third of DOL torque; heavy or high-resistance loads may not accelerate, so check the load torque curve.
Inputs
I_Y = I_Δ/3 | T_Y = T_Δ/3 | U_phase,Y = U_line/√3Calculation model (updates with parameters)
| DOL line current I_st,Δ | 600 A | I_n × 启动×数 |
| Star line current I_st,Y | 200 A | 降为直接启动的 1/3 |
| DOL starting torque T_st,Δ | 200 N·m | T_n × 启动转矩×数 |
| Star starting torque T_st,Y | 66.67 N·m | 降为直接启动的 1/3 |
| Star phase voltage U_phase | 219.4 V | U_线/√3，380V 系统≈ 220V |
| Load starting torque T_L | 30 N·m | 30% × T_n |
| Starting torque margin | 2.22 × | recommend ≥1.15× |
| Starting result | 可以启动 ✓ | 星形转矩大于load阻Force矩 |
Engineering notes
- Star-delta starting applies only to motors designed for delta running with six accessible terminals; star duration depends on starting current and speed.
- Star starting torque is only one third of DOL torque; heavy or high-resistance loads may not accelerate, so check the load torque curve.
- Switching causes a second inrush; use a star-delta starter with transfer delay and interlock, or a soft starter / VFD when needed.
FAQ
- What is Star-Delta Starting Current / Torque for?
- Compare direct-on-line and star-delta starting line current, starting torque, and star phase voltage; check whether the load can start.
- What is the formula for Star-Delta Starting Current / Torque?
- Core formula: I_Y = I_Δ/3 | T_Y = T_Δ/3 | U_phase,Y = U_line/√3. The tool returns results instantly using this formula and the selected parameters.
- What engineering notes should I keep in mind when using Star-Delta Starting Current / Torque?
- Star-delta starting applies only to motors designed for delta running with six accessible terminals; star duration depends on starting current and speed. Star starting torque is only one third of DOL torque; heavy or high-resistance loads may not accelerate, so check the load torque curve. Switching causes a second inrush; use a star-delta starter with transfer delay and interlock, or a soft starter / VFD when needed.