Sync-Guard Feature Overview



When multiple zero cross controllers are connected to the same power source, the result can be a high peak current; the controllers switch from on to off at the same time, requiring very high current and then no current.

This can result in:

  • Fluctuations in power, causing flickering lights and potential damage to electronics
  • Increased risk of a blown fuse or overloaded transformer.
  • Higher utility costs

To address these problems, we developed SYNC-GUARD, a trademarked technology that reduces peak current requirement by causing multiple controllers to fire in turn.

Here we have a scope reading of two zero-cross controllers connected to one power source and operating without SYNC-GUARD. Once we enable SYNC-GUARD, the peak current falls and the current demand is more consistently at 50% duty cycle.

We've connected the two controllers to light bulbs to demonstrate how each fires in turn: one is firing while while the other is off.

SYNC-GUARD was designed to be used with a maximum of ten controllers.

This scope shows Sync-Guard's impact with all ten controllers running. This top line marks the current demand if all ten controllers are firing at once, the middle line is 50 %, and the bottom line if none are firing.

Even with SYNC-GUARD enabled, occasionally multiple controllers will still fire at the same time. The probability of this happening is highest when many controllers transition into the RUN state and turn on at the same time. SYNC-GUARD may not eliminate this occurance altogether, but overall it ensures a much more consistent current draw.

For more information, you can visit our website at, or contact the experts directly at Control Concepts, Inc.