AS NZS IEC 60947.4.2:2015 pdf free download – Low-voltage switchgear and controlgear
5.3.5.3.1 Starting characteristics of squirrel cage and hermetic refrigeration motors
a) One direction of rotation with the inclusion of phase-control capability to provide any combination of controlled acceleration to normal speed, controlled deceleration to standstill, or an occasional manoeuvre without de-energizing the controller (AC-53a, AC- 58a).
b) One direction of rotation with the inclusion of phase-control capability to provide controlled acceleration to normal speed. Controllers and starters are rated for intermittent duty only (AC-53b, AC-58b); for example after starting, the motor may be connected into a circuit that bypasses the power semiconductors.
Two directions of rotation may be accomplished by reversing the connections to the controller or motor by means that are beyond the scope of this standard, but are covered by the relevant product standard for the selected means. Two directions of rotation may also be accomplished by phase reversing within the controller or starter. The requirements for this operation will vary with each application. Therefore, this is subject to agreement between manufacturer and user. Due to the control capability of controllers and starters, the current during starting, stopping, and any manoeuvre will differ from the conventional values of the prospective locked rotor current listed in Table 1 1 .
5.3.5.3.2 Starting characteristics of rheostatic rotor starters with controllers energizing the stator (AC-52a, AC-52b)
Starters can be used to provide reduced voltage excitation to the stator windings of a slip ring motor, and thereby reduce the number of switching steps required in the rotor circuit. For most applications, one or two starting steps are adequate depending upon load torque and inertia, and the severity of start required. NOTE Starters and controllers covered by this standard are not intended for use in the rotor circuit and therefore, the rotor circuit must be controlled by traditional means. The relevant product standards for the rotor circuits of rheostatic rotor starters should apply.
Each utilization category (see Table 2) is characterized by the values of the currents, voltages, power-factors and other data of Table 3, Table 9, Table 1 0 and Table 1 1 , and by the test conditions specified in this standard. The first digit of the utilization category identification designates a semiconductor switching device (for example within this standard a semiconductor motor controller or starter). The second digit designates a typical application. The a-suffix designates the capability of a controller to perform any of the functional possibilities listed in Table 1 . The b-suffix designates the capability of a controller where it is restricted to performing a transition from an OFF-state to a starting function of duration T x , and immediately returning to the OFF-state to comprise a duty cycle in accordance with the requirements of 8.2.4.1 .