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PICOAMMETER TYPE CP13
1. INTRODUCTION
The CP13 is a combined DC ammeter and generator for use over the
current range
12x10-3A FSD to 12x10-14A FSD in 23 ranges.
An additional range enables charge to be measured with an FSD of
12pC. As an ammeter, it maintains its virtual earth input
within 50mV
of earth for signals from zero to FSD and has an equivalent input
drift typically less than 50mV
over 1 hour after an initial 10 minutes settling period. As a
generator, it has an equivalent source voltage of greater than 1kV
and will tolerate a load voltage deviation from earth of more than
1.5V.
2. PERFORMANCE SPECIFICATION
(At 20oC except where otherwise stated and after 10 minutes settling period)
As the same measuring components are used for current generate and current measure, the specification for the two modes is identical. It follows that the range trimming potentiometers may be set using either operating mode.
2.1 Error and Stability
Range (FSD) |
Error ±%
|
Temp Coef ppm/oC |
Stability typ. ±%/annum |
|
|
EXT DVM |
INT METER |
|
|
12x10-3A and 4x10-3A |
0.3 |
1.5 |
±50 |
0.1 |
12x10-4A to 4x10-8A |
0.2 |
1.5 |
±50 |
0.1 |
12x10-9A to 4x10-10A |
1.0 |
2.0 |
±100 |
0.1 |
12x10-11A to 4x10-11A |
1.0* |
2.0* |
±150 |
0.1 |
12x10-12A to 12x10-14A |
2.0* |
3.0* |
-1200 typ. |
0.5 |
*This
does not include the error due to residual current which is less
than ±1x10-14A
(typically ±2x10-15A).
2.2 Zero Shift
With temperature: ±100mV/oC max
With input signal: 50mV max (zero to FSD)
With time: ±50mV/hour typical
2.3 Residual Current Less than ±1x10-14A, typically ±2x10-15A
2.4 Current Generator
Apparent voltage: Greater than 1kV
Load voltage: ±3.0V max