vibrating wire strain gauge

Embedment gauges are cast directly into fresh concrete and measure internal strain. Spot‑weld types attach to reinforcement bars before pouring; they tell you what the steel is doing. On a bridge deck, you often use both: embeds for the slab itself and spot‑welds on the girders below. Kingmach can supply either configuration with the same cable specs so you do not end up with two different readout setups on one site.

Yes, if the cable connection is handled correctly. The gauge body itself is sealed, but the splice between the gauge cable and the extension cable is the weak point. On dam and marine projects, installers typically cast the splice inside epoxy‑potted junction boxes or run the factory‑attached cable all the way to the readout station. Kingmach’s standard cable jacket is pressure‑rated up to 1MPa for short‑term submersion, but for permanent underwater use the team can supply a polyurethane‑jacketed option with molded seals at the gauge end.

Any readout that excites the coil and reads the frequency response—most dataloggers from Campbell Scientific, Geokon, or Kingmach’s own KMS‑150 series. You measure the period in microseconds, square it, and multiply by the gauge factor from the calibration sheet. If the project already uses a multiplexer, Kingmach’s gauges come with color‑coded conductors that match common wiring schemes, so the field crew does not have to re‑pin connectors.

Yes, we often shorten the standard 165mm body to 120mm or 140mm if the rebar layout is tight. The gauge factor shifts slightly with the shorter wire length, so each sensor gets a unique calibration certificate. Ordering 20‑50 units at a time keeps the cost per gauge reasonable, and lead time is about two weeks on average.

The frequency signal is immune to cable resistance changes, so length is rarely an issue for measurement accuracy. Installers have successfully run 500m spans with no drop in reading quality. The practical limit comes from the cable capacitance affecting the excitation pulse; beyond 800m you may need a heavier‑gauge conductor or a line driver, which Kingmach can provide as a small inline module.