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This document is a technical datasheet for the Oneida Zenamic Metal Oxide Varistor (ZMOV) series, specifically models Z7, Z10, Z15, Z21, and Z33. These devices function as Transient Voltage Suppressors with a non-linear current-voltage characteristic designed to sustain an almost constant voltage over a wide range of current.
The change in clamping voltage (Vd) must be less than 10%, and the outside surface appearance should not be affected.