HP 34970A manual Gi u, AC Measurement and Operating Characteristics

Chapter 9 Specifications

AC Measurement and Operating Characteristics

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AC Measurement Characteristics [1]

True RMS AC Voltage	AC-coupled True RMS – measures
Measurement Method:
	the ac component of input with up
	to 300 Vdc of bias on any range
Crest Factor:	Maximum 5:1 at Full Scale
Additional Crest Factor
Errors (non-sinewave): [2]	Crest Factor 1-2: 0.05% of reading
	Crest Factor 2-3: 0.15% of reading
	Crest Factor 3-4: 0.30% of reading
AC Filter Bandwidth:	Crest Factor 4-5: 0.40% of reading
	3 Hz – 300 kHz
Slow
Medium	20 Hz –	300 kHz
Fast	200 Hz –	300 kHz
Input Impedance:	1 MΩ ± 2%, in parallel with 150 pF
Input Protection:	300 Vrms on all ranges
Frequency and Period	Reciprocal counting technique
Measurement Method:
Voltage Ranges:	Same as AC Voltage function
Gate Time:	1s, 100 ms, or 10 ms
Measurement Timeout:	Selectable 3 Hz, 20 Hz, 200 Hz LF limit
True RMS AC Current
Measurement Method:	Direct coupled to the fuse and
	shunt. AC-coupled True RMS
	measurement (measures the
	ac component only)
Shunt Resistance:	5Ω for 10 mA; 0.1Ω for 100 mA, 1A
Input Protection:	1.5A 250 V fuse on HP 34901A module
Measurement Noise Rejection [3]
AC CMRR:	70 dB

Measurement Considerations (Frequency and Period)

All frequency counters are susceptible to error when measuring low-voltage, low-frequency signals. Shielding inputs from external noise pickup is critical for minimizing measurement errors.

AC Operating Characteristics [4]

Function	Digits [5]	Readings/s	AC Filter
ACV, ACI:	61⁄2	7 sec/reading	Slow (3 Hz)
	61⁄2	1	Medium (20 Hz)
	61⁄2	8 [6]	Fast (200 Hz)
	61⁄2	10	Fast (200 Hz)
	61⁄2	100 [7]	Fast (200 Hz)
Single Channel Measurement Rates [8]

Function	Resolution			Readings/s
ACV:	61⁄2		Slow (3 Hz)	0.14
	61	⁄2	Medium (20 Hz)	1
	61	⁄2	Fast (200 Hz)	8
	61	⁄2	[7]	100
Frequency, Period:	61⁄2		Digits (1s gate)	0.77
	61	⁄2	Digits (1s gate) [7]	1
	51	⁄2	Digits (100 ms)	2.5
	51	⁄2	Digits (100 ms) [7]	9
	41	⁄2	Digits (10 ms)	3.2
	41	⁄2	Digits (10 ms) [7]	70

[1]300 Vrms isolation voltage (ch-ch, ch-earth)

[2]For frequencies below 100 Hz, slow AC filter specified for sinewave input only

[3]For 1 kΩ unbalance in LO lead

[4]Maximum reading rates for 0.01% of ac step additional error. Additional settling delay required when input dc level varies.

[5]61⁄2 digits=22 bits, 51⁄2 digits=18 bits, 41⁄2 digits=15 bits

[6]For external trigger or remote operation using default settling delay (Delay Auto)

[7]Maximum limit with default settling delays defeated

[8]For fixed function and range, readings to memory, scaling and alarms turned off

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