How it works

Power, conditioned in series.

Most protection waits for a problem, then reacts — diverting a spike after it has already begun. Bantam works differently: the circuit sits in the current path and conditions everything flowing through it, continuously. Here is the mechanism, from the circuit up.

The core idea

Three moves, one circuit.

The whole architecture rests on three ideas. Everything below is detail on how they are built and what they measure.

In series with the load

The conditioning circuit sits in the current path, not beside it. Everything the equipment draws passes through it, so it shapes power continuously rather than waiting to react to a spike.

The inductor goes first

A series inductor on every conductor opposes any rapid change in current. It meets a fast surge edge with high impedance, limits how quickly current can build, and shapes the leading edge before anything downstream has to.

The clamps are governed

Because the inductors absorb the worst of the edge first, the all-mode varistors engage on an already-shaped waveform. They act as saturation governors — a difference in role that keeps protection from wearing down.

The mechanism

A series inductor on every conductor, clamped in every mode.

Every Bantam product places a series inductor on Line, Neutral, and Ground, paired with metal-oxide varistors across every mode combination — Line–Neutral, Line–Ground, and Neutral–Ground, extending in polyphase systems to every conductor pairing. The inductors are the working mechanism. An inductor opposes any rapid change in current through it (v = L·di/dt), so it presents high impedance to a fast edge and limits how quickly current can build into the downstream equipment.

During a surge, the inductor shapes the steep leading edge and stages the clamps; at energization, the same inductance limits in-rush current. The all-mode varistors then ensure no conductor pairing — differential or common mode — lets a transient reach the load unclamped.

The inductors use Sendust (iron-silicon-aluminum) distributed-gap cores, whose inductance rolls off gradually as current rises rather than collapsing abruptly at saturation. Meaningful series inductance keeps suppressing through the worst part of a large surge — precisely when it matters most — and because the inductors are permanently in the current path, edge-shaping begins with the transient itself, not after a clamp has reached its threshold.

Series inductors on L, N, and G shape the incoming edge; varistors clamp every mode — L–N, N–G, and L–G. Dots mark connections; the small hop marks a crossing that is not connected.

The role difference

The varistors are present on every mode — the inductors change the job they have to do. Staged behind the inductors, the clamps engage on a pre-shaped waveform and see a small fraction of the energy a clamp-only device absorbs. That is a difference in role, not the absence of a component, and it is what keeps protective performance from degrading over repeated events.

See it work

One circuit, five jobs.

The same series architecture does five things to the power passing through it. Select one to see what changes between what comes in and what reaches the equipment.

Incoming To equipment

< 0.2% surge residual reaching the equipment

What it measures

Measured, not asserted.

The architecture's behavior has been measured and independently verified by NTS Labs. The headline figure is what actually reaches the protected equipment during a surge.

< 0.2% surge residual — more than 99.8% of destructive surge energy kept from the equipment.

up to 30%

power-factor improvement

up to 40%

reduction in odd-order harmonics

100 / 60 dB

line-to-neutral / ground attenuation, 100 Hz–1 GHz

Figures are measured results stated as ranges. The methodology, independent reports, and white papers behind them are available on request — see Technical documentation.

Go deeper

The mechanism is one part of the picture.

The proof