CTB size 1

Current transformer CTB size 1


CTB size 1

bushing current transformer, encapsulated in epoxy resin •  highest permissible system up to 36 kV  •  rated primary currents up to 3 kA  •  option: airtight bushing

Current transformers of CTB type are designed for indoor use at medium voltages. Epoxy resin casting (containing wounded cores inside) is the main electrical insulation. Excellent parameters of electrical insulation (including low level of partial discharges) are guaranteed.

CTB current transformers size 1 are used in all applications where small dimensions and high rated dynamic currents are necessary, for example in tapping busducts of power generators.

The primary current winding is made of copper conductor with silvered terminals. The length, size and type of terminals are manufactured according to Client’s requirements.

The epoxy resin castings of CTB current transformers size 1 are manufactured in various lengths, so the overall dimensions are optimised, according to the quantity of cores (max. 4 cores in standard execution) and their rated outputs.

CTB current transformers can be mounted in any position.

Technical data:

highest permissible system voltage7.2/12/17.5/24/36 kV
power frequency withstand voltage, 1 min20/28/38/50/70 kV
impulse withstand voltage 1.2/50 µs60/75/95/125/170 kV
rated frequency50 or 60 Hz
rated primary current IPn75 – 3 000 A
rated short–time thermal current Ith1s150 kA/1s (r.m.s. value)
rated dynamic current Idyn250 kA (peak value)
number of coresup to 4
rated secondary currents ISn1 A or 5 A or fractional
rated outputs Sn5 – 90 VA
accuracy classes0.2, 0.2S, 0.5, 0.5S, 5P, 10P, PX, PR
instrument security factor (FS)5, 10, 15
accuracy limit factor10, 20, 50
ambient temperature–25oC ÷ 80oC
weightca 20 – 45 kg
according to standardsPN-EN 61869-1:2009; PN-EN 61869-2:2012


CTB size 1
dane techniczne
CTB size 1
technical data
CTB size 1
Certyfikat ISO