TDH, TA, TP, TC, TRP — LV measuring and protection current transformers (60–5000 A)

Technical specifications

Specifications are taken from the manufacturer’s technical documentation. Updated 11/06/2026.

Description

TDH are bushing-type transformers for 60–4000 A with a window of 20–63 mm, which can be sealed and are supplied with a test report. TDH5 125/5A has a 20 mm window for busbars of 15 × 15, 20 × 10 or 25 × 5 mm, a safety factor of 5 and a dynamic current of 2.5 Ith. TA with a closed core are rated for 750–5000 A and busbars from 20 × 100 to 60 × 125 mm; TA400 300/5A gives 5 VA in class 0.5, 10 VA in class 1 and 15 VA in class 3. TP have a split core for 75–5000 A, busbars from 30 × 30 to 160 × 80 mm, a lock in TP-10 and TP-12, and TP8 200/5 has a 60 × 80 mm window, class 3 and 1.5 VA. TC are powered from the measured network and output 0–20 or 4–20 mA at currents of 50–300 A, with a 28–44 mm window and busbars from 40 × 10 to 60 × 12 mm. TRP are cast in resin with a 40–180 mm window. The operating voltage is up to 0.72 kV, and the thermal current is 60 In.

How to choose

First determine the primary current and the size of the busbar or cable. If the supply can be switched off during installation, take TDH for metering or TA for large currents, otherwise TP with a split core. TC are needed when 0–20 or 4–20 mA must be supplied to a controller. For protection relays in panels and cells, TRP from 100/5 to 5000/5 A of classes 5P10 and 5P20 are intended.