High Resistance Insulation Materials
When you reach an electrical resistance of 1 Giga Ohm,
The measurements are difficult and the resistance reading is very
unstable. After 10 M itself, resistance is affected by the humidity of
the room and the dust on the resistor. High resistance measurement, can
evaluate the resistance of the paint on a resistor or even a small
piece of wood.
I had a set of Victoreen
Resistors which were in thin sealed glass bulbs, like large reed
relays from 1G Ohm to 1T ohm. High
Resistance measurement is possible from test voltages of 100V to 1000V.
The leakage current can provide data for evaluating resistance. In
components like transformers, it will take a long time for a stable
reading, so the charge, discharge, leakage of the Coil Capacitance can
help
measure Insulation Resistance or polarization index.
Liquids
| 20 C |
OHM |
-M |
|
min |
max |
| Benzene |
1011 |
1012 |
| Transformer oil |
1010 |
1013 |
| Gasoline |
1010 |
1013 |
| Castor oil |
108 |
1010 |
| Acetone |
104 |
105 |
| Ethanol |
104 |
105 |
| Distilled water |
103 |
104 |
Glass At High Temperature
| 200 C |
OHM -M |
| Sodium Pyrex |
2 * 106 |
| Potassium Pyrex |
8 * 109 |
| Lead glass |
2 * 1011 |
Effect Of Contamination On Surface Resistivity
| 70% RH |
CONTAMINATED |
CLEAN |
| Window glass |
2 * 108 |
1012 |
| Fused quartz |
2 * 108 |
1013 |
Relation Of Resistivity With RH % And Temp
| MATERIAL |
70% RH 20 deg C |
0% RH 100 deg C |
0% RH 20 deg C |
| Marble |
106 - 108 |
1010 - 1012 |
1012 - 1014 |
| Wood |
106 - 107 |
1010 - 1012 |
1011 - 1013 |
| Vulcanized fibers fibers |
106 - 109 |
108 - 109 |
1011 - 1012 |
| MATERIALS |
SOLIDS OHM -M |
Solids
| MATERIALS |
OHM -M |
| Polyethylene |
1017 |
| Poly propylene |
1017 |
| PVC |
1018 |
| Polyurethane |
1015 |
| Asbestos fiber + phenol |
108 |
| Mica + phenol |
1012 |
| Glass-fiber + polyester |
1012 |
| Glass-fiber + epoxy |
1014 |
|
