What is a split-core current transformer (KBR/KBU)?
Split-core current transformers (KBR/KBU) have a divisible, hinged measuring core. This allows them to be mounted around an already laid, non-separable line – a clear advantage when retrofitting measuring technology in existing systems without having to touch the existing wiring.
When a split-core current transformer is the right choice
Split-core current transformers are always suitable when the line to be measured is already permanently installed and cannot or should not be separated – for example, when subsequently installing measuring technology in existing control cabinets. They therefore differ from plug-on current transformers (ASK), which require an existing busbar or round conductor for plugging on, and from wound-type current transformers (WSK) with a permanently wired primary winding, which are intended more for new installations with smaller currents. A more detailed classification can be found in our selection guide; if you are unsure, please feel free to contact us.
Technical features
- Divisible, hinged measuring core for subsequent installation
- Primary current from 50 A to 5.000 A
- Secondary current 1 A or 5 A or optionally 4-20 mA or 333 mV available
- Accuracy classes 0,5, 1 and 3
Installation and safety
The secondary circuit of a current transformer must never be operated open during operation – before disconnecting measuring devices in the secondary circuit, it must be short-circuited. When using a divisible measuring core, additionally ensure that it fully and cleanly engages when closing – a remaining air gap can affect measurement accuracy.
Versions at a glance
The available KBR/KBU variants differ in size, transformation ratio and accuracy class – the complete overview can be found in the product list above. If you have any questions about the right selection for your application, please feel free to use our contact form or give us a call.
Frequently asked questions
Immer dann, wenn die zu messende Leitung bereits fest verlegt ist und nicht aufgetrennt werden kann oder soll – etwa bei nachträglicher Messtechnik-Installation in bestehenden Schaltschränken. Für neu verlegte Leitungen oder Sammelschienen ist der ASK meist die einfachere Wahl.
Der Messkern ist teilbar und aufklappbar und lässt sich so um die bestehende Leitung schließen, ohne die vorhandene Verkabelung zu unterbrechen oder neu anzuschließen.