10.1 Coil protection

   If possible, the coil and core should be kept at the same potential level whenever the coil is “on” or “off”, to avoid the electrochemical corrosion.

10.2 Contact protection

   There are many protective circuits to protect the contact. For inductive load, diode in parallel connection with the load is generally used to eliminate sparkle; RC absorption network or voltage-sensitive resistance in parallel connection with the contact is used to protect the contact. To capacitive load or lamp load, little power resistance or RL suppressing network in series is generally used in the loop circuit to suppress the shock from surge current.