Current transformer (called CT), may only be short-circuited or operated with a negligible load impedance because open current transformers "run hot" and destory themselves. Apart from that, load impedances lead to measuring inaccuracies in electricity supply meters and hence to financial losses for their operators. Therefore, Laplace-Electric Ltd. cooperated with Weidmuller create a teaching video convenient for maintenance.

Video of CT terminal: http://www.lel.hk/en/support.php