Increase Neutral Return Current
on 15kV Single Phase Lines

The CBT equalizes phase and neutral currents, allowing only those currents flowing to the farm on the primary to return on the primary neutral. Current from any other source is rejected. If current does not enter through the CBT primary winding it cannot return through the neutral winding. "Off Farm" current is prevented from using the farm's grounding system to flow to or from the utility's neutral. 

An added benefit is harmonic or transient common mode (longitudinal) voltage spike attenuation (primary line and neutral line to remote earth), thus reducing coupling into the farm secondary system through the (step down) distribution transformer. In essence, the CBT functions as a common mode choke filter to swamp out harmonics and spikes.

15kV CBT - P31111
25kV CBT - P31121 (shown)
US Patent No. 5,914,842

Transverse or normal mode (phase to neutral) harmonic currents are pulled back and not allowed to flow in the farm grounding system as a result of the balancing action of the CBT, which also effectively reduces EMF fields.

The CBT magnetically couples the primary phase conductor and neutral conductor, forcing the return current to travel through the neutral rather than through other paths. The magnetic field created by the return current in the neutral cancels the field created by the current from the phase conductor, thereby eliminating magnetic fields in the core. In short, the CBT isolates the power system from the environment while allowing the power system to remain properly grounded

This single phase transformer must be installed by a power utility on a pole for a primary distribution feeder single phase load tap to limit stray currents at the step down transformer neutral grounding point.

SNC will provide a CBT to your utility for a 60 day free trial.

Features/Benefits:

• Voltage reduction of seven to one or higher is common, often to less than one-tenth of a volt!
  

• Primary and secondary neutrals and bonding remain safely connected in accordance with National Electrical Safety Code (NESC Rule 97B).

• Completely passive device - no electronic components to fail.

• Sold only to electric power utilities.

• Ask about our satisfaction/money back guarantee.

15kV Technical Data: (25kV model available April, 2000)

• Single Phase, 15 kV Two Wire Service

• Rated to 7 Ampere, 60Hz, 55°C Rise

• Series Impedance: 0.044 Ohms at 75°C Under Balanced Loading

• Certified to withstand 1,000 Amperes rms of fault current for 2.5 cycles, 60 Hz (40ms) to exceed clearing time of a 15 Amp T-link fuse.  It also carries a 95kV impulse rating.

• Automatic Line Powered Neutral Line Shorting Switch Available

• Weight: 180 lbs. (82 kg).

• Testing per ANSI/IEEE C57.12.90 (Impulse - clause 10.3;
  Voltage - clause 10.6; Short Circuit - clause 12)

For More Information

Call 1-800-558-3325 or 920-231-7370.