Megger Digiflex Com - Page 50

50 man_digiflex_com_en_02_5.doc
6.2 Conversion: NVP 
v
/
2
Conversion NVP 
v
/
2
(
m
/
s
)
2
s
m
299.79 • NVP
=
2
v

Conversion
v
/
2
(
m
/
s
)  NVP
s
m
299.79
2
v
• 2
= NVP

6.3 Table: NVP and
v
/
2
for Common Types of Cables
Typical propagation time
Insulation
v
/
2
, m/µs
v
/
2
, ft/µs NVP
Oil-impregnated paper 75-84 246-276 0.50-0.56
Poly, cross-linked 78-87 256-285 0.52-0.58
Poly, filled with Petrolat 96.0 314.8 0.64
Polyethylene 100.5 329.6 0.67
PTFE 106.5 349.3 0.71
Paper 108-132 354-433 0.72-0.88
Poly, foamed 122.9 403.4 0.82
Air 141-147 462-482 0.94-0.98