Power Accessories

For information on all power accessories including, line and load reactors, isolation transformers, input RFI filters and dynamic braking (DB) resistors please see our Options & Accessories brochure. On this page you will also find a link to a Power Accessories Dimensions PDF that includes mounting dimensions for all our power accessories listed above.

Line and Load Reactors

Line reactors (sometimes called “line chokes”) are a common power accessory for electronic variable speed drives. These components add an extra margin of protection for AC and DC drives from supply transients.

Line reactors are strongly recommended for installation with AC drives that do not have built-in inductors. Load reactors are used on the output of AC drives to reduce the effects of high motor wiring capacitance and to “soften” the dV/dt (rate of change of voltage) applied to the motor windings.

Isolation Transformers

Drive isolation transformers add an extra margin of protection for AC and DC drives. They are sized to the drive kVA requirements and are designed to withstand the mechanical stress of current reversals and short circuits associated with power semiconductor type AC and DC drives.

  • Three-coil, delta-wye configuration with fully rated NEMA 1 enclosure
  • ±5% fully rated taps on primary winding
  • Ambient temperature: 104 °F (40 °C)
  • Standards: ANSI C89.2, NEMA ST-20, UL506, UL1561

Drive EMC Filters

Electromagnetic Compatibility Filters

EMC filters are used to minimize high-frequency power supply line disturbances caused by drives that may interfere with proper operation of sensitive electronic equipment. These specific filters have been assessed for conformance with the EMC directive by testing with the appropriate Control Techniques drives. EMC data sheets are available for digital drive products.

These data sheets list the applicable harmonic standards and give recommended installation techniques and further information on EMC behavior in typical situations. All Control Techniques AC and DC drives include internal EMC filters.

Dynamic Braking Resistors

Dynamic Braking (DB)

The DC bus voltage level of an AC drive increases while the motor is re-generating (i.e. ramping to a stop). Dynamic braking resistors provide a means of rapidly stopping a rotating motor and load while maintaining an acceptable bus voltage level. The kinetic energy stored in the spinning mass is converted into electrical energy and quickly dissipated as heat through a resistor. Control Techniques offers resistor kits available for both AC and DC drives.

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