Fluke - 887A - Analog multimeter
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Equipment:
887A
Date:
1967
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Information
The 887A/AB series instruments are capable of being used as
conventional voltmeters for rapid determination of voltages
from 0 to 1100 volts dc and from 0.00:1 to 1100 volts ac to
within ±3% of range setting; as differential voltmeters for
precise measurement of dc voltages from 0 to ±1100 volts to
within ±(0.0025% of input + 0.0001% of range + 5juv); as
accurate ac voltmeters for measurement of ac voltages from
0.001 to 500 volts to within ±(0.05%of input + 0.0025% of
range) from 30 Hz to 5 kHz, with reduced accuracy to 5 Hz
and 100 kHz; and as megohm-meters for measurement of
resistance from 10 megohms to 11,000 megohms with a typical
accuracy of 5%. They can also be used to measure the
excursions of a voltage about some nominal value. One
feature that should be emphasized is that no current is
drawn from the unknown source at null up to 11 volts dc.
Thus the determination of the unknown potential is
independent of its source resistance. Above 11 volts dc, the
input resistance is an excellent 10 megohms. To minimize
errors due to common mode voltages, the 887 A series is
provided with extremely high leakage resistance to ground -
- typically several hundred thousand megohms. Also, where
ground loops errors are a problem, the battery operated mode
of the 887AB eliminates these errors due to complete
isolation from the power line. As additional features, the
887A series contains a polarity switch for equal convenience
in measuring positive or negative dc voltages and an
adjustable recorder output which makes the instrument
particularly useful for monitoring the stability of almost
any ac or dc voltage. Furthermore, thorough shock,
vibration, humidity, and temperature testing assure years of
hard use under severe environmental conditions.
When used as a dc differential voltmeter, the 887A operates
on the potentiometric principal. An unknown voltage is
measured by comparing it to a known adjustable voltage with
the aid of a null detector. An accurate standard for
measurement is obtained from 11 volt dc reference supply
derived from a pair of temperature-compensated zener diodes.
The known adjustable reference voltage is provided by a
Kelvin-Varley voltage divider with four decades of FLUKE
precision wirewound resistors and a high-resolution
interpolating vernier that are set accurately by five
voltage readout dials to give a six digit readout. In this
way, the 11 volts can be precisely divided into increments
smaller than 10 microvolts. The unknown voltage is then
simply read from the voltage dials. For voltages between 11
and 1100 volts dc, an input attenuator divides the unknown
voltage by 100 before it is measured potentiometrically.
When used as an accurate ac voltmeter, the 887A operates
essentially the same as for dc differential measurements.
The ac input voltage is converted 10 a dc voltage and this
dc voltage is measured by comparing it to a known adjustable
reference voltage.
2 Manuals
Service and user manual
Manual type:
Service and user manual
Pages:
24
Size:
1.5 MB
Language:
english
Revision:
2
Manual-ID:
Date:
August 1973
Quality:
Scanned document, reading partly badly, partly not readable.
Upload date:
Jan. 15, 2018
MD5:
ff31b077-3b11-fa9d-8a3d-f18cf6dc6bb9
Downloads:
1547
Service and user manual
Manual type:
Service and user manual
Pages:
62
Size:
6.0 MB
Language:
english
Revision:
Manual-ID:
Date:
February 1967
Quality:
Scanned document, reading partly badly, partly not readable.
Upload date:
Jan. 20, 2018
MD5:
bedd2cf6-81da-29d4-33e4-be5e0b676cbb
Downloads:
1299