| Subject | English | Spanish |
| coal. | operating relay for protection against failure of earth continuity | relé de protección de continuidad de tierras |
| mech.eng., construct. | phase failure relay | relé de falta de fase |
| PSP | relay failure for elementary relays | fallo de relé para relés elementales |
| PSP | relay failure rate | tasa de fallo de un relé |