15 Jul 2021
Weidmuller's TTB measuring transformer terminal block series 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. North American approvals UL/CSA (cURus) are available as well. The measuring transformer terminals of the TTB series have been 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 prevents high voltages from occurring in the secondary winding. The "close-before-open" contact for up to four connections ensures 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 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. The TTB series carries an electrical rating of 300-600V/5-30A/AWG 22-8.
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