Local control supply straight from the 11 kV or 33 kV busbar — no LT auxiliary needed.
HT control transformers step the high-voltage supply directly from 11 kV or 33 kV busbars to 110V or 240V for powering trip coils, protection relays, annunciators, and auxiliary circuits in high-voltage switchgear. At locations where there is no separately derived LT supply — rural substations, ring main units, compact secondary substations — the HT control transformer is what keeps the protection and control system energised. It is a safety-critical component: if it fails, the circuit breaker cannot trip.
Sakthi manufactures HT control transformers to IS 5142 and IEC 61558 with CRGO cores and Class F/H insulation, in ratings conservatively derated for continuous 24/7 duty in an unattended substation environment. The units are compact by design — space is always at a premium inside HT switchgear panels — and are constructed to withstand the vibration, temperature cycles, and occasional voltage transients that are normal inside an operating substation.
Typical applications
Steps down 11 kV or 33 kV to safe 110V/240V control supply for HT breaker trip coils, relays, and interlocking circuits.
Powers protection relay panels, trip circuits, and annunciator systems in 11 kV and 33 kV substations.
Supplies auxiliary power to RTUs, IEDs, and SCADA interfaces in automated 11 kV and 33 kV substations.
Standard component for HT switchgear manufacturers, ring main unit (RMU) assemblies, and compact substation builders.
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