Motor Starting Impedances
They are used for starting three-phase asynchronous motors with squirrel-cage rotor and their use is envisaged where star-delta starting is not possible, and in particular in those drives where the resisting torque is increasing with speed as in the case of pumps, fans and compressors. They are also used in cases where starting must be slow and without torque jumps (textile machines, spinning mills, etc.), being able to exclude the impedance near nominal speed in these cases. The sizing of these impedances is for short-duration operation and their insertion at nominal starting values is expected for a time of 60 seconds, which normally corresponds to about 3÷6 consecutive motor starts. The impedances of this series are custom-built and for a single voltage to be specified in the order, provided it does not exceed 600 Volts. Starting impedances with different torque reduction values, or with additional regulation taps can be requested.
| Technical characteristics | |
|---|---|
| Reference standards | IEC 61558 |
| Voltage on motor | equal to 70% of V mains |
| Starting torque | reduced to 50% |
| Starting current | reduced to 70% compared to what would be with direct insertion |
| Thermal insulation class | F |
| Reference ambient temperature | 40° C |
| Protection degree | IP00 |
| Suitable for installation up to | IP2x |
| Connections | Terminal block or output bar |