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ELECTRICAL PARAMETERS |
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Resistance Values
Whilst E24 values are
preferred, other values are readily available at no additional cost. |
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Resistance Tolerance
± 20%, ± 10% and ± 5% available
as standard. |
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Resistivity Range - ρ
3 Ohm cm to
30000 Ohm cm
ρ = R x A/L, where
R = Resistance Value |
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Temperature Coefficient - TCR
-0.05% to -0.15% per °C Temperature Rise depending on Resistivity Value.
TCR = 0.16 x e
-(log ρ / 1.4) - 0.135
(% / °C Temperature Rise) |
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Voltage
Coefficient - VCR
-0.5% to
-7.5% / kV / cm
VCR = -0.62 x ρ 0.22
(% / kV / cm)
For ρ domain 10 to 7500 Ohm cm |
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Inductance
This is negligible (nH) and the resistors may be
described as non-inductive. In practice the inductance of connecting leads
will be greater than that of the resistors. |
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Dielectric Constant
(Permittivity) εr
This is very
difficult to measure and will vary according to material resistivity.
As an order of merit :
єr
≈ 5 |
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Maximum Working Voltage Withstand per cm of Disc Length (V
wk) |
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Volts
(rms) |
SF6 |
V wk =
1.00 x (R/t x A/L)
0.335 |
kV/cm |
} |
t Domain 10 to
50 ms |
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↑ |
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AIR |
V wk =
.87 x (R/t x A/L)
0.3 |
kV / cm |
t = Insertion
time in ms |
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ρ Domain 10
to 7500 Ohm
cm |
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Volts (Impulse) |
SF6 |
V wk =
8.0 x
1.2
√ Log (R/2.54 x A/L) |
kV / cm |
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1.2 / 50 µs
Waveform |
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AIR |
V wk =
4.3 x 1.2
√ Log (R/2.54 x A/L) |
kV / cm |
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1.2 / 50 µs
Waveform |
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AIR |
V wk =
3.0 x Log (R/2.54 x A/L) |
kV / cm |
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50 / 1000 µs
Waveform |
↓ |
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AIR |
V wk =
1.5 x (Log (R/2.54 x
A/L))
1.25 |
kV / cm |
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100 / 10000 µs
Waveform |
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