Lovato Base Mounted Current Transformer, 150:5

The DM series current transformers are installed in electric installations to reduce the line current to a secondary value of 5 A, which is compatible with current inputs of digital multimeters or protection relays.
These are without primary winding and are used for high primary current values from 50 A upward.
The number of loops of the primary cable does not modify the accuracy but converts the primary current value proportional to secondary current.