Low Voltage Drive Isolation Transformers

• Evaluated according to UL Standard 1561 for effects of harmonic heating
• Designed for typical harmonics per IEEE 519-1992
• Meets 4% minimum reactance for 150°C temperature rise designs
• Conforms to IEEE-597 Class B overload, which requires 150% of load for one minute per hour
• Designed for the mechanical stress of dc drive current spikes
• Designed for the thermal and mechanical stress of highly cyclic process control applications

Drive isolation transformers provide reactive control of current harmonics for both AC and DC motor drives, either static bridge or SCR switch input type.

Reducing current harmonics has two benefits:

1. It decreases line current waveform distortion, which improves the power factor of the motor drive load.
   
   
2. It reduces voltage waveform distortion effects in the feeders ahead of the transformer. Reducing voltage distortion can prevent motor drives from affecting sensitive loads, even other motor drives, elsewhere on the service.

Many loads have characteristics similar to AC and DC motor drives. This is transformers because the load inputs are either designed with 3-phase static diodes or 3-phase, 6-pulse, SCR bridge rectifier circuits. Drive isolation transformers can also control the effect of these loads on the primary power system. General equipment applications for drive isolation transformers include:

• SCR controlled heating or furnaces
• 3-phase rectifier input dc power supplies
• 3-phase switched-mode power supplies