HSD fuse, Nordellectronica ne237

[IRHP]

Anyone know what it means when it shows on an item such as Pump no 6 e.g. HSD 5A? ( SEE PIC) It doesn't seem to be a replaceable fuse on the unit.
All items with HSD are switched on at the panel.

 

[BouncyBoatFolk]

High Speed Data ?
Mike.

 

[IRHP]

High Speed Data ?
Mike.

The fact it quotes 5amp I wouldn't think so but thanks for the suggestion. More like some sort of resettable trip I think.
High speed disconnect?