In 18kV transformers, temperature monitoring shall be done by three Pt-100 temperature probes (4-wire) inserted in the prospective hot-spot of the secondary windings (one per phase). An additional 4-wire Pt-100 probe shall be installed in the hottest part of the S-phase winding.

The output terminals shall be wired to an auxiliaries connection box (IP 33) mounted on the front side of the transformer’s enclosure:  this connection box houses a terminal strip to collect and group all the auxiliary wiring from the temperature probes.

A two-level thermal protection system giving two independent potential free normally closed contacts, opening on alarm/fault, to signal alarm and trip levels of the transformers temperature shall be provided to the CERN Electronic Controller. For this, a temperature-monitoring T-935 -40ºC/+200ºC from TECSYSTEM s.r.l. (Italy) is used.