Accuracy zone
Your device’s accuracy at 25°C (77°F) and 40% relative humidity.
| A | Zone A: Accuracy is 20% ± 1 digit | ||
| B | Zone B: Accuracy is 5% ± 1 digit | ||
| C | Zone C: Accuracy is 50% ± 1 digit | ||
| D | Resistance at accuracy zone limit τ1 | ||
| E | Resistance at accuracy zone limit τ2 (10 MΩ maximum) | ||
Assuming two significant digits for insulation resistance measurements the accuracy can be calculated.
-
Zone A: At 250 Ω, 20% = 50, ± 1 digit = 10. Displayed value will range from 190 Ω to 310 Ω, for an overall accuracy of approximately ± 25%.
-
Zone B: At 1 kΩ, 5% = 50 Ω, ± 1 digit = 100. Displayed value will range from 1.8 kΩ to 1.2 kΩ, for an overall accuracy of approximately ± 20%.
-
Zone C: At 3 MΩ, 50% = 1.5 MΩ, ± 1 digit = 100 kΩ. Displayed value will range from 1.4 MΩ to 4.6 MΩ, for an overall accuracy of approximately ± 50%
Calculation of resistance for accuracy zone limitsτ1, τ2
τ = R (MΩ) x C(µF)
The accuracy of your device transitions at specific τ values, identified by testing at different resistances and capacitances, and is also influenced by the filtering (measurement sample duration) selected.
-
For filtering of 4 seconds, τ1 = 1, τ2 = 4
-
For filtering of 40 seconds or 160 seconds, τ1 = 2, τ2 = 10
Resistance at τ1 and τ2 with 4 second filtering
| τ1 = 1 | τ2 = 4 |
|
Capacitance = 1 µF , τ1/C = 1/1 µF = 1MΩ Resistance at τ1 = 1 MΩ |
Capacitance = 1 µF , τ2/C = 4\1 µF = 4MΩ Resistance at τ2 = 4MΩ |
|
Capacitance = 10 µF , τ1/C = 1/10 µF = 100 kΩ Resistance at τ1 = 100 kΩ |
Capacitance = 10 µF , τ2/C = 4/10 µF = 400 kΩ Resistance at τ2 = 400 kΩ |
| Accuracy zone B (5%) range is approximately | |
Resistance at τ1 and τ2 with 40 second and 160 second filtering
| τ1 = 2 | τ2 = 10 |
|
Capacitance = 1 µF , τ1/C = 2/1 µF = 2MΩ Resistance at τ1 = 2MΩ |
Capacitance = 1 µF , τ2/C = 10\1 µF = 10 MΩ Resistance at τ2 = 10 MΩ |
|
Capacitance = 10 µF , τ1/C = 2/10 µF = 200 kΩ Resistance at τ1 = 200 kΩ |
Capacitance = 10 µF , τ2/C = 10/10 µF = 1 MΩ Resistance at τ2 = 1 MΩ |