Operating characteristics of protective relays in positions other than vertical

While electromechanical protective relays are designed to operate in the upright position, which is the manner in which they are normally used, some applications, such as on ships, may require these relays to operate normally while exposed to tilting and oscillatory motion. A variety of electromechanical and solid-state protective relays were tested for pickup and time-delay characteristics while tilted in several directions from vertical and while undergoing oscillatory motion. These test showed that induction disk and induction cup relays were seriously affected by tilting and motion, but that hinged-armature and solid-state relays were not affected