Weidmuller’s TTB measuring transformer terminal block series is a unique systematic offering of modular terminals that meet all the connection requirements of critical transformer (current/voltage) protection and measurement functions. The series is approved according to IEC 60947-7-1 Annex D – safety-relevant components captively connected to the modular terminal block. In addition, North American approvals; such as, UL/CSA (cURus) are available as well.
The measuring transformer terminals of the TTB series have been specially developed for use in secondary circuits of measuring transformers. For safe application when disconnecting or isolating protection of measuring devices, the terminal short-circuits the current transformer and thus prevents high voltages from occurring in the secondary winding. One of the most important advantages of the new transformer terminal is the “close-before-open” contact for up to four connections. It ensures that the current transformer within the terminal is short-circuited before it is disconnected from the rest of the transformer circuit. This prevents the voltage at the current transformer from running up and protects it from damage or even destruction. After short-circuiting the current transformer (CT) side and simultaneously disconnecting the primary side, the meter can be easily and safely checked via relay test or replaced. The combination of a disconnecting lever and short-circuit bridge in a single system provides the possibility of forced short-circuit functionality to guarantee simple and safe wiring.
Thanks to the patent-pending Comparative Measurement (CM) lever connection, two-terminal blocks can be selectively disconnected in order to interconnect a calibrated measuring device. After the measurement, the captive lever is reset to the original position, leaving the “close-before-open” contact active which is a unique feature of the TTB series that guarantees the highest safety for personnel and equipment. The switching state of the TTB series instrument transformer terminals is easily visible in all lighting conditions based on color-coding. The disconnect lever can be operated by hand or with a standard screwdriver. It also facilitates the realization of multi-pole actuations.
The measuring transformer terminal blocks of the TTB series also adapt flexibly to different customer specifications. The integrated combination foot allows mounting on the two common mounting DIN rail profiles TS32 and TS 35. In addition, the terminal blocks are available with either PUSH IN or screw connection technology. A transparent protective cover system is available for particularly sensitive applications. Its cover can only be fixed when all connection components are in their initial position. In this way, the assembly is comprehensively protected against incorrect operation, unauthorized access, and contamination without impairing visual inspection.
The TTB series carries an electrical rating of 300-600V/5-30A/AWG 22-8