Manual

ManualsBrandsAmerican Magnetics ManualsEquipment150A Portable Liquid Helium Level Meter (CE-Marked)

1 March 6, 2001

INSTALLATION, OPERATION AND MAINTENANCE

INSTRUCTIONS FOR THE AMI

MODEL 150A

LIQUID HELIUM LEVEL METER

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.

II. SPECIFICATIONS (at 25 °C unless stated otherwise)

Input Power (instrument) Sealed lead-acid battery (6VDC)

Input Power (AC adapter)

90VAC to 132VAC 50/60 Hz, or 180VAC to 264VAC

50/60 Hz (depending on specified AC adapter model)

Operating temperature (instrument) 0 to 50 °C non-condensing

Operating temperature (AC adapter) 0 to 40 °C non-condensing

Sensor active length range 1 inch to 60 inches

Linearity

0.5% of full scale

Absolute Calibration 0.5% of full scale

2% of full scale (from 0 to 50 ºC)

Probe Current 75 mA nominal

Battery Life Typically 1,000 readings with a 60" sensor.

Summary of content (7 pages)

PAGE 1
INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS FOR THE AMI MODEL 150A LIQUID HELIUM LEVEL METER 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.
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III. INSTALLATION A. Carefully remove the instrument from the shipping carton and remove all the packing material. Inspect the equipment for any physical damage that may have occurred during shipment. NOTE: If there is any shipping damage save all packing material and contact the shipping representative to file a damage claim. Do not return the instrument to AMI unless prior authorization has been received. (See Section IX) IV. B.
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Fig. 1.
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V. MAINTENANCE A. The instrument was shipped with a full charge on the batteries. Operating under a maximum power consumption of measuring a 60" sensor in a near empty dewar, the unit is capable of making approximately 1,000 level measurements before battery recharging is required. B. The failure of the front panel LED to light when a measurement is being made indicates low battery power. If the front panel LED fails to stay lit during a measurement, the batteries should be recharged.
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1. ONLY IF NEEDED (see above note), remove the electronics from the enclosure to allow access to the printed circuit board, by following the steps in this section. NOTE: The electronics inside the instrument are STATIC ELECTRICITY sensitive. Extreme care should be used when handling by following static sensitive handling procedures. 2. Open the Model 150A enclosure by loosening the four captive lid screws. 3.
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B. IV. ACTIVE LENGTH CALIBRATION 1. Jumper the I+ and V+ contacts (pins 1 and 8)on the SENSOR connector together and connect to one side of the calibration resistor. Jumper the I- and V- contacts (pins 6 and 7) on the sensor connector together and connect to the other side of the calibration resistor. The value of the calibration resistor should be (4.56 ohms) x (the active length of the sensor in cm); remember that the active length of AMI standard sensors is 1 inch less than the overall length. 2.
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B. C. Meter reads 100.0 when the READ switch is depressed. 1. Verify that a sensor is properly connected to the instrument. 2. Ensure the helium level is not actually at the top of the sensor. Other erroneous level indications. Most inoperative instruments are traced to improper wiring between the sensor and the instrument. Verify the sensor is connected in accordance with the color code outlined in the installation section (see table in installation section and Figure 1).