NHP TemBreak PRO, User Manual

Page: 19 / 105

Installation
19
TemBreak PRO
B_BE-UM-001-EN
– V1.1.0
Clearances
Phase to Phase and Earth
Interruption of large currents during fault or normal switching operation produces ionised gases and arcing materials which expelled from the vents at the top
of the MCCB. These ionised gases are highly conductive, concentrated, and at an elevated temperature when it exits the MCCB via the arc vents. Care
must be taken to avoid an arcing fault from occurring due to the presence of concentrated ionised gases creating a conductive path between exposed
conductors. Incoming conductors must therefore be insulated the full length up to the terminal opening of the MCCB, ensuring bare conductors are not
exposed directly to concentrated ionised gases. This also applies to the attached busbars supplied as part of the MCCB.
Interpole barriers or terminal covers may be used to achieve creepage and clearance requirements. Conductors must not impede the flow of ionised gas
and allow it to clear and disperse safety. Interpole barriers are supplied as standard with Terasaki MCCBs for the line side only. 2 barriers with 3P MCCBs
and 3 with 4P MCCBs. In cases where two different MCCB types are installed one above the other, the insulation distance between the two models should
be as for the lower model.
WARNING : Exposed conductors including terminals at attached busbars must be insulated to avoid possible
short-circuit or earth faults due any foreign matter coming into contact with the conductors.