SIRIUS Charge Module
https://dewesoft.com/products/daq-systems/sirius/tech-specs
Specifications
| Charge ranges (Low Range) | ±100 000 pC (5000 pC) | ±10 000 pC (500 pC) |
| Input accuracy (HPF 0.1 Hz) | ±0.5 % of reading ±20 pC | ±0.5 % of reading ±5 pC |
| Typ. Dynamic Range @ 10 kS (Dual Core) | -130 dB (-150 dB) | -120 dB (-140 dB) |
| Typ. Noise floor @ 50 kS (Dual Core) | 107 dB (120 dB) | 105 dB (118 dB) |
| Input coupling | 0.01 Hz, 0.03 Hz, 0.1 Hz, 0.5 Hz, 1 Hz, 10 Hz or 100 Hz | |
| Charge injection | 1 Vrms, 20 Hz, 0.5 % accuracy | |
Charge
Q = C * V
Q = Charge [C = Coulomb]
C = Capacitance [F = Farads]
V = Voltage [V = Volts]
Example:
V signal = 1 Vrms
Capacitor = 1 nF
Charge Q = C * V = 1 nC = 1000 pC
Input coupling - Charge module
| HP filter setting (Coupling), 10 kpC and 100 kpC -3 dB Frequency (Hz) | Comment |
| 0.01 | Charge Filter |
| 0.03 | Charge Filter |
| 0.1 | Charge Filter |
| 0.5 | Charge Filter |
| 1 | Combined 0.1 Hz Charge Filter and 1 Hz IEPE Filter |
| 10 | Combined 0.1 Hz Charge Filter and 10 Hz IEPE Filter |
| 100 | Combined 0.1 Hz Charge Filter and 10 Hz IEPE Filter |
| Charge Reset (see image below) | Combined 0.5 Hz Charge Filter and 100 Hz IEPE Filter |
Charge reset
If Reset is selected for short time a combined 0.5 Hz Charge Filter and 100 Hz IEPE Filter are enabled for fast charge offset reset. Afterwards filter is set to previous selected option.
Options also available in Channel setup:
Both will be applied to all Charge channels in setup.
Charge Generator
Enable / Disable Charge Generator
MR = 100 kpC, 1nF on input, 11 kpC ACrms measured.
MR = 10 kpC, 1nF on input, 2 kpC ACrms measured.
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| MR = 10 kpC, open input, 1 kpC ACrms measured. | MR = 100 kpC, open input, 10 kpC ACrms measured. |
Sample test report:
NOTE:
Reference and measured result on the report are 11 kpC, the same as on example above. For both measurements 1 nF reference capacitor was used.
Hint:
1 Vrms can be measured on open BNC input connector when Charge Generator is Enabled.
Capacity target check
Capacity target check will evaluate combined capacitance of sensor and measurement cable. In case of sensor or cable break or fault this would be detected.
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| Enter a valid number. | Press - Check. |
Measurement in progress. Takes few seconds.
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Result is evaluated. | If error > 10% it is indicated in red. |
Hint:
Typical coax cable capacitance is 100 pF per meter. Eg. 100 m cable will add 10000 pF or 10 nF capacitance.
In the above example 11 nF target capacitance should be entered.
Warning:
Depending on MR and target capacitance input could be in OVL and measurement of target capacitance will not be correct.
Note:
Capacity target check is not required, nor it is mandatory for sensor measurement. Field can be left blank!
Warning: known issue
Entering a negative scaling factor for Sensitivity will not return correct result.
Jernej Kovačič, 09.04.2021