American Magnetics 150 Installation, Operation And Maintenance Manual

INSTALLATION, OPERATION AND MAINTENANCE
I. INTRODUCTION
The American Magnetics, Inc. (AMI) Model 150A is a compact, fully portable Liquid Helium
Level Meter providing simple and easy operation. The instrument is battery operated and when
used in conjunction with an AMI LHe Level Sensor, provides a truly portable means of
measuring liquid helium levels at any location. The sensor connects to the instrument via a
standard DB9 connector. The instrument displays 0-100% of sensor maximum active length
immersed in LHe. The instrument can be used with AMI sensors with active lengths of up to 60
inches. The instrument is powered by sealed lead-acid batteries. A standard AC-DC adapter
(either 120VAC or 230VAC) is supplied with the unit for charging the batteries. Since battery
energy consumption is strongly dependent on the LHe level being measured, AMI has developed
a special "battery saver" circuit which reduces the power drain from the batteries as more of the
sensor becomes superconducting. Power requirements decrease as LHe level increases. A front
panel POWER LED is provided to indicate sufficient battery power exists to make an accurate
level reading.
The CE mark applies to the handheld unit and the European AC adapter. The North American
AC adapter is not CE marked.
II. SPECIFICATIONS (at 25 °C unless stated otherwise)
Input Power (instrument)
Input Power (AC adapter)
Operating temperature (instrument)
Operating temperature (AC adapter)
Sensor active length range
Linearity
Absolute Calibration
Probe Current
Battery Life
* Under extreme radiated electromagnetic field conditions (3V/m @ 80MHz to 1GHz) the
accuracy may be degraded by an additional +/- 1.2%
INSTRUCTIONS FOR THE AMI
MODEL 150A
LIQUID HELIUM LEVEL METER
Sealed lead-acid battery (6VDC)
90VAC to 132VAC 50/60 Hz, or 180VAC to 264VAC
50/60 Hz (depending on specified AC adapter model)
0 to 50 °C non-condensing
0 to 40 °C non-condensing
1 inch to 60 inches
0.5% of full scale
0.5% of full scale
2% of full scale (from 0 to 50 ºC)
75 mA nominal
Typically 1,000 readings with a 60" sensor.
1 August 18, 2003