HPFF vs Solid dielectric cable 1

[Mbrooke]

What, if any advantage do HPFF cables have over solid dielectric cables? 115 through 345kv.

 

[waross]

Here's an Okonite brochure.

http://okonite.com/okonite-wire-and-cable-product-brochures/Pipe-Type 2014 small.pdf

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Mbrooke]

It makes a case for pipe cable, but isn't cost off set by the pump system?

 

[waross]

Well Okonite does make pipe cable and can be expected to push the advantages of HPFF.
I thought the comparison chart may be useful in that it gives you some questions to ask and verify independently.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Mbrooke]

I found it very useful Just inquiring further. Today, when 115 and 345kv transmission lines need to be buried, is the gravity toward HPFF or XLPE? Or is it solely driven on each individual application? I am not the brightest bulb, but to me HPFF does not appear practical in new installations.

 

[cuky2000]

MBrooke, if you are in the US, it is hard to justify the SCFF cable for land application since the standard installation practice in the States is to run single conductor cable in a duct bank or encased in pipe for HPFF cable.

Most utility today prefer XLPE because the environment concern with potential oil spill. If oil filled cable need to be used, most utility prefer HPFF because the minimum space required, better mechanical protection and potential to cool the oil and control the line capacity.

For submarine application, the majority of the oil cable used is SCFF. If there is chance to direct burying the cable, or the phase have to be segregated for installation or safety reasons, SCFF have a chance to be used since its ampacity performance are better than the HPFF as shown in the graph below

 

[Mbrooke]

But in Europe, the tradition is solid dielectric cable when used on land? The two main issues for me are:

1. Loss of electric supply results in dropping pressure. This can increase restoration time in that power must first be applied to the substation from an external source.

2. Fault finding and repair appears far more difficult. I'd rather skip all the extras needed. Here is a good blog on that:

http://hackaday.com/2015/07/27/find...ed-power-cable-feels-like-mission-impossible/

 

[FPelec]

In Europe SCFF cables are much more used than HPFF for underground cable lines ; HPFF was almost never used, wheras SCFF was commonly until the '80s even for lower transmission voltages (let's say up to 170 kV). SCFF was also used until the 2000s for the highest voltages (245 to 420 kV in ac and 400 kV in dc). However all the new projects, up to 420 kV, uses solid (XLPE) insulation.

Si duri puer ingeni videtur,
preconem facias vel architectum.

 

[FPelec]

However, to reply to the origina question, for new installations it does not make any sense to use HPFF cables instead of solid insulation ones such as EPR, XLPE, or thermoplastic materials(eg P-Laser).
HPFF have some significant drawbacks if compared to solid insulation, the most significant being cost and environmental issues.


Si duri puer ingeni videtur,
preconem facias vel architectum.

 

[Mbrooke]

SCFF is self contained fluid filled?


I see it much the same way with HPFF. While I have some sense, would you happen to know how reactance, capcitance, and surge impedance differs in solid dielectric cables vs HPFF?

 

[FPelec]

Mbrooke:
Yes, SCFF is self containerd fluid filled.
For the same voltage and cross-section, the capacitance of a solid insulated cable is generally lower if compared to HPFF due to the lower permittivity of XPLE if compared to paper-oil insulation. The surge impedance thus is generally higher in XLPE cables.
SCFF cables can use paper oil insulation (in this case their capacitance is almost the same of HPFF ones) or mixer Paper-Polypropylene Laminated (PPL) insulation; in the latter case their capacitance is lower if compared to HPFF but still somewhat higher than XLPE ones.

Si duri puer ingeni videtur,
preconem facias vel architectum.

 

[Mbrooke]

But inductance is higher due to the fact each phase is further apart on XLPE cables?