415V Crane Fuse Protection

[CalumMcKay]

Hi,

I am trying to size a fuse for a crane with the following spec:
- Peak Current - 176A
- Peak Power - 122kVA
- Continuous Current (simultaneity factor - 0.8) - 124A
- Peak Current - 176A
- Length of run - 30m
- Fuse for site power - 124A(min) / 143A(max)

Do I provide fuses and cabling that are rated to the peak or continuous values? This is where my confusion lies. If I design it to the peak power it is over the max fuse for site power. Unless the fuse for site power is located at the crane? Crane model is 370 EC-B 12 Fibre if that helps any.

Thanks,
Calum

 

[Besoeker3]

Hi,

I am trying to size a fuse for a crane with the following spec:
- Peak Current - 176A
- Peak Power - 122kVA
- Continuous Current (simultaneity factor - 0.8) - 124A
- Peak Current - 176A
- Length of run - 30m
- Fuse for site power - 124A(min) / 143A(max)

Do I provide fuses and cabling that are rated to the peak or continuous values? This is where my confusion lies. If I design it to the peak power it is over the max fuse for site power. Unless the fuse for site power is located at the crane? Crane model is 370 EC-B 12 Fibre if that helps any.

Thanks,
Calum

Do you mean peak or RMS? Normally we use RMS. And these days three-phase is 400Vrms.

 

[Jraef]

Not sure if it’s the same in the UK as it is here, but I imagine it would be.

You size the conductors for the continuous power x 1.25, then size the fuses to what the conductor rating Is. Use time-delay fuses to handle the momentary surge current when the motor starts.

 

[JEFF MILLAR]

If I understand you correctly, this as you have written makes no sense. How can you supply the crane with 176 A ?
With a Fuse for site power rated 124 A / 143 A ( Max ) You need to clarify this. Have you a simple one line ?