| Style of starter |
Stator resistance starter (for squirrel-cage motors) |
Rotor starter (for slipring rotors) |
| 2) Type of starter |
Star-delta switches |
With starting resistors |
With starting transformers |
Rotor resistance starter |
| 3) Number of starting stages |
1 only |
Normally 1 |
Normally 1 |
Selectable (no longer selectable when current or torque have been determined) |
| 4) Voltage reduction at the motor |
0.58 × rated operational voltage |
Selectable: a × rated operational voltage (a < 1) e.g. 0.58 as with   starter |
Selectable: 0.6/0.7/0.75 ×Ua (transformer tappings) |
None |
| 5) Starting current taken from mains |
0.33 × inrush current at rated operational voltage |
a × inrush current at rated operational voltage |
Selectable (see 4) 0.36/0.49/0.56 × inrush current at rated operational voltage |
Selectable: from 0.5 to about 2.5 × rated current |
| 5a) Starting current at the motor |
As above |
As above |
Selectable (see 4) 0.6/0.7/0.75 × Ie |
As above |
| 6) Starting torque |
0.33 × tightening torque at rated operational voltage |
a2 × tightening torque at rated operational voltage |
Selectable (see 4) 0.36/0.49/0.56 × tightening torque at rated operational voltage |
Selectable (see 5) from 0.5 to pull-out torque |
| 7) Current and torque reduction |
Proportional |
Current reduction less than torque reduction |
Proportional |
Current reduction much greater than torque reduction. From pull-out torque to rated speed almost proportional |
| 8) Approximate price (for similar data). DOL starting = 100 (with overload relay, enclosed) |
150–300 |
350–500 |
500–1500 |
500–1500 |
