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The AC/DC sensitive measuring current transformers of the CTUB103 series convert system leakage and fault currents into an evaluable measurement signal. The devices are suitable for detecting fault currents with smooth DC components. They consist of a CTBC… measuring current transformer core and a CTUB103 electronic module, which can be combined to suit the application. The measuring current transformers can be used in DC, AC and 3(N)AC systems as well as in high-resistance grounded systems for monitoring the star point. The evaluation in resistance grounded systems is carried out with devices of the NGRM… series, to which the measuring current transformers are connected.


  • Multicolour LED for operation, fault and status messages
  • Electronic module can be exchanged without mechanical separation of the primary conductors
  • Monitoring of the connection to the measuring current transformer
  • Evaluator: NGRM500, NGRM550, NGRM700, NGRM750

Downloads for LINETRAXX® CTUB103

CTUB1xx 88.4 KB 2022/08/12 06:17:2412.08.2022 06:17:24
CE Declarations of Conformity CTxx 89.3 KB 2022/11/04 06:57:2904.11.2022 06:57:29
CE Declarations of Conformity CTUB1xx 88.4 KB 2022/08/12 06:17:2412.08.2022 06:17:24
Datasheets CTUB103 403.5 KB EN2020/10/29 06:46:2229.10.2020 06:46:22D00410
Manuals CTUB103 671.3 KB EN2022/09/27 12:34:5027.09.2022 12:34:50D00410

Optional Accessories for LINETRAXX® CTUB103

CTUB103 sets

Setø current transformersPermissible measuring rangeArt. No.
CTUB103-CTBC3535 mm5 A, 10 AB78120030
CTUB103-CTBC6060 mm5 A, 10 A, 25 AB78120031
CTUB103-CTBC120120 mm5 A, 10 A, 25 AB78120032

Voltage supply

TypeMax. connected current transformersArt. No.
STEP-PS/1 AC/24 DC/0.52B94053110
STEP-PS/1 AC/24 DC/1.757B94053111
STEP-PS/1 AC/24 DC/4.217B94053112

Replacement parts - Measuring current transformer cores

Typeø current transformersArt. No.
CTBC3535 mmB98120003
CTBC6060 mmB98120005
CTBC120120 mmB98120007

Replacement parts - Electronic modules

TypeUSArt. No.
CTUB103DC 24 VB78120052

Required terminals are optionally available.


Type designationArt. No.
Snap-on mounting for CTBC35B91080112

(included in scope of delivery)