6 Reasons to Choose Synchronous, Zero-Voltage Close Capacitor Switches

3-phase, synchronous, zero-voltage close capacitor switches keep amusement park rides rolling at Missouri ammusement park.

When the Silver Dollar City amusement park in Branson, MO installed the Outlaw Run, one of the world’s steepest wood roller coasters, the loads caused by the ride tested the capacitor bank that ensured stable power quality to the park.

In the past, the oil-filled capacitor switches used on the bank were able to maintain power quality for the amusement park. The capacitors, when turned on, quickly charged from zero voltage to whatever the line voltage was.

After the ride was installed, however, the process of switching on capacitors generated over-voltage transients large enough to trip the vacuum fault interrupters (VFIs) on the switch gear used for overcurrent protection on the capacitor bank.

White River Valley Electric Cooperative, the amusement park’s electric utility, needed to eliminate the large voltage transients that were tripping the VFIs and shutting down the ride. The utility chose to change out the oil-based capacitor switches previously used on the capacitor bank to Trinetics SmartCloseÒ 3-phase, synchronous, zero-voltage close capacitor switches.


The solution worked so well that engineers at White River Electric are planning to use synchronous, zero-voltage close capacitor switches again on another capacitor bank serving the park.

“They are in the process of installing a new ride, and we want to make sure that our capacitor switching operations on are not going to cause any issues for the newer high-tech control systems that are going to be on that ride,” said Reiny Cash, chief engineer, White River Valley Electric Cooperative.

Making the change to synchronous, zero-not only eliminated the transients but allowed the utility to:

1: Eliminate re-striking voltage

This type of voltage, also called transient recovery voltage, appears across the breaker contacts when they open and often results in harmful voltage spikes caused by short-duration high frequency.

2: Improve installation processes

White River’s solution did not require a secondary controller to receive signals from the main controller. Eliminating the secondary controller simplified installation and made multiple calibration exercises between the secondary controller and switch unnecessary.

3: Ensure maintenance-free operation

The dielectric switch technology chosen by White River operates in a vacuum chamber instead of under oil. Over time, switch contacts operating in oil build up carbon and must be maintained. No such carbon build-up occurs in a vacuum, making dielectric switches virtually maintenance free.

4: Cut capital expense

Dielectric switches are rated for 50,000 operations, giving them decades more service than oil-based switches, which are typically rated for 2,000 operations.

5: Decrease recalibration requirements

After years of operation, mechanical switches will slow down, and must be calibrated with their controllers. The capacitor switch technology chosen by White River automatically adjusts to changes in switch operation.

6: Reduce line losses

The capacitor switch technology picked by the utility add capacitance in sensitive areas where it’s crucial to minimize power quality issues that capacitor switching operations could cause.


For more information on how White River benefited from synchronous, zero close switch technology, download the case study.


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