American Magnetics 187 User Manual

EXCELLENCE IN MAGNETICS AND CRYOGENICS

AMI

MODEL 187 LIQUID LEVEL

CONTROLLER

INSTALLATION, OPERATION, AND

MAINTENANCE INSTRUCTIONS

American Magnetics, Inc.

PO Box 2509, 112 Flint Road, Oak Ridge, TN 37831-2509, Tel: 865 482-1056, Fax: 865 482-5472

March 1998

Model 187 Liquid Level Controller

Model 187 Configuration

AMI Order Number:_____________________

Shipping Date:_________________________

Model 187 Serial #:______________________

Firmware Revision:_____________________

Input Power Requirements:___________________________________________________________

Sensor Length (mm):_____________________________________________________________

Calibration Passcode:____________________

Maximum Dielectric: _________________

Configuration Notes:

_____________________________________________________________________________________

AMI Warranty

All products manufactured by AMI are warranted to be free of defects in materials and

workmanship and to perform as specified for a period of one year from date of shipment. In

the event of failure occurring during normal use, AMI, at it s opt ion, will r epair o r repla ce a ll

products or components that fail under warranty, and such repair or replacement shall

constitute a fulfillment of all AMI liabilities with respect to its products. Since, however,

AMI does not have control over the installation conditions or the use to which its products

are put, no warranty can be made of fitness for a particular purpose, and AMI cannot be

liable for special or consequential damages. All warranty repairs are F.O.B. Oak Ridge,

Tennessee, USA.

Purpose and Scope

.....................................................................

Contents of This Manual

..........................................................

Applicable Hardware

...............................................................

General Precautions

.................................................................

Cryogen Safety

..............................................................

Safety Summar y

......................................................................

vii

Recommended Safety Equipment

..............................

viii

Safety Legend

.............................................................

viii

1.1

Model 187 Features

...................................................................

1.1.1

Compensated capacitance-based level sensing

............

1.1.2

Factory calibration

........................................................

1.1.3

Convenient display and direct keypad entry

...............

1.1.4

Automatic level contro l

.................................................

1.1.5

Remote computer monitoring or controlled operation

.21.2

Front Panel Layout

..................................................................

1.3

Rear Panel Layout

.....................................................................

1.4

System Diagram

.......................................................................

1.5

Model 187 Specifications @ 25

°C.............................................

2.1

Unpacking the Instrument

.......................................................

2.2

Rack Mounting the Instrument

................................................

2.3

Installing the Sensor

.................................................................

2.4

Connecting the Model 187 to the Sensor

.................................

2.5

Installing the Optional Solenoid-Operated Fill Valve

..........

2.6

Connecting the Instrument to Power

.....................................

3.1

Operational Guidelines

...........................................................

3.1.1

Energizing the instrument

..........................................

3.1.2

Selecting the Appropriate Units

.................................

3.1.3

Configuring the Length Settings

................................

3.1.4

Configuring the HI and LO Alarms

............................

3.1.5

Configuring the A and B Setpoints

.............................

3.1.6

Selecting the Fill Mode

................................................

3.1.7

Configuring the Fill Timer

..........................................

Foreword................................................................................... v

1 Introduction.............................................................................. 1

2 Installation................................................................................ 7

3 Operation................................................................................ 13

Table of Contents

3.2

Sensor contamination

..............................................................

3.3

Menu Reference

........................................................................

3.3.1

Accessing Menus

..........................................................

3.3.1.1

Entering Numerical Values

.............................

3.3.1.2

Menu Option Selection

.....................................

3.3.1.3

Exiting Menus

..................................................

3.3.2

HI Menu

........................................................................

3.3.3

LO Menu

.......................................................................

3.3.4

A Menu

..........................................................................

3.3.5

B Menu

..........................................................................

3.3.6

RATE Menu

..................................................................

3.3.7

LEN (Length) Menu

.....................................................

3.3.7.1

Zero Offset

.........................................................

3.3.7.2

Measured Span

.................................................

3.3.8

FILL Menu

....................................................................

3.3.8.1

Fill Mode

...........................................................

3.3.8.2

Fill Timeout

......................................................

3.3.9

MUTE Menu

.................................................................

3.3.10

COMM Menu

................................................................

3.3.10.1

Display Contrast

.............................................

3.3.10.2

IEEE-488 Address

...........................................

3.3.10.3

Serial Bau d R a te

.............................................

3.3.10.4

Serial Data Bits/Parity

...................................

3.3.10.5

Serial Sto p B i ts

................................................

3.3.10.6

Serial Handshaking

........................................

3.3.11

CAL Menu

.....................................................................

4.1

SCPI Command Summary

......................................................

4.2

Programming Overview

...........................................................

4.2.1

SCPI Language Introduction

.......................................

4.2.2

SCPI Status System

.....................................................

4.2.2.1

Status Byte Registers

.......................................

4.2.2.2

Serial Polling and the Service Request (SRQ)

4.2.2.3

Reading the Status Byte using *STB?

............

4.2.2.4

Using the Message Available Bit(s)

.................

4.2.3

Standard Event Registers

............................................

4.2.4

Alarm Registers

............................................................

4.2.5

Command Handshaking

..............................................

4.2.5.1

Using the

Command

...............................

4.2.5.2

Using the

Query

....................................

4.2.6

Remote Units

................................................................

4.3

RS-232/422 Configuration

.......................................................

4.3.1

Serial Port Connector

...................................................

4.3.2

Termination Characters

...............................................

4 Remote Interface Reference..................................................27

*OPC *OPC?

Table of Contents

4.3.3

Flow Control Modes

.....................................................

4.4

IEEE-488 Configuration

.........................................................

4.4.1

Termination Characters

..............................................

4.4.2

Device Clear

.................................................................

4.5

Command Reference

...............................................................

4.5.1

System-Related Commands

........................................

4.5.2

Status System Commands

..........................................

4.5.3

Alarm Configuration Commands and Queries

..........

4.5.4

Level and Usage Queries

............................................

4.5.5

Length Configuration Commands and Queries

.........

4.5.6

Fill Mode Control and Queries

...................................

4.5.7

Calibration Commands and Queries

..........................

4.5.8

Remote Units Commands and Queries

......................

4.6

Error Messages

........................................................................

4.6.1

Command Errors

.........................................................

4.6.2

Query Errors

................................................................

4.6.3

Execution Errors

..........................................................

4.6.4

Device Errors

...............................................................

5.1

Model 187 Maintenance

..........................................................

5.2

Model 187 Troubleshooting Hints

..........................................

5.2.1

The Model 187 does not appear to be energized

with the power switch in the

) position.

....525.2.2

The Model 187 does not remember the alarm

setpoints after power is remov ed.

...............................

5.2.3

The Model 187 displays “Over/Under Flow”.

.............

5.2.4

The Model 187 displays “Max Diel Exceeded”.

..........

5.2.5

The liquid level unexpectedly drops rapidly as

the tank level approaches 100%.

................................

5.2.6

The liquid level unexpectedly rises rapidly as

the tank level approaches 0%.

....................................

5.2.7

The USER and FACTORY calibrations do not

yield the same liquid level.

.........................................

5.2.8

The Model 187 is not responding to remote

communications commands.

.......................................

5.3

Additional Technical Support

.................................................

5.4

Return Authorization

..............................................................

5 Service .................................................................................... 51

32:(5 (,

iii

Table of Contents

A.1

4-20 mA Current Loop Option

.................................................

A.2

Auxiliary Connector J8 Pinout

................................................

A.3

IEEE-488 Connector

................................................................

A.4

RS-232/422 Connector

..............................................................

Appendix..................................................................................57

Index.........................................................................................63

Foreword

This manual contains the operation and maintenance instructions for the

American Magnetics, Inc. Model 187 Liquid Level Controller. The manual

outlines the instructions for instrument use in various system designs.

Since it is impossible to cover all possible system/sensor designs, the most

common configuration is discussed and the user is encouraged to contact

an authorized AMI Technical Support Representative for infor mat i on

regarding specific configurations not explicitly covered in this manual.

Introduction

introduces the reader to the functions and char acteristics of

the instrument. It provides the primary illustrations of the front and rear

panel layouts as well as documenting the performance specifications.

Installation

describes how the instrument is unpacked and installed in

conjunction with ancillary equipment in a typical cryogenic system.

Operation

describes how the instrument is used to measure and control

liquid level.

All

instrument displays and controls are documented.

Remote Interface Reference

documents all remote commands and

queries available through the RS-232 and IEEE-488 interfaces. A quick-

reference summary of commands is provided as well as a detailed

description of each.

Service

provides guidelines to assist the user in troubleshooting possible

system and instrument malfunctions. Information for contacting AMI

Technical Support personnel is also provided.

The

Appendix

documents the rear panel co n n e ct o rs.

Purpose and Scope

Contents of This Manual

Foreword

The Model 187 has been designed to operate with an AMI Liquid Level

Sensor. Operation with other equipment is not recommended and may

void the warranty.

Personnel handling cryogenic liquids should be thoroughly instructed and

trained as to the nature of the liquids. Training is essential to minimize

accidental spilling. Due to the coldness of these materials, a cryogen

spilled on many objects or surfaces may damage the surface or cause the

object to shatter, often in an explosive manner.

Inert gases released into a confined or inadequately ventilated space can

displace sufficient oxygen to make the local atmosphere incapable of

sustaining life. Cryogenic liquefied gases are potentially extreme

suffocation hazards since a small amount of liquid will vaporize and yield

a very large volume of oxygen-displacing gas. Always ensure the location

where the cryogen is used is well ventilated. Breathing air with

insufficient oxygen content may cause unconsciousness without warning.

If a space is suspect, purge the space completely with air and test before

entry. If this is not possible, wear a forced-air respirator and enter only

with a co-worker standing by wearing a forced-air respirator.

Cryogenic liquids, due to their extremely low temperatures, will burn the

skin in a similar manner as would hot liquids. Never permit cryogenic

liquids to come into contact with the skin or allow liquid nitrogen to soak

clothing. Serious burns may result from careless handling. Never touch

uninsulated pipes or vessels containing cryogenic liquids. Flesh will stick

to extremely cold materials. Even nonmetallic materials are dangerous to

touch at low temperatures. The vapors expelled during the venting process

are sufficiently cold to burn flesh or freeze optic tissues. Insulated gloves

should be used to prevent frost-bite when operating valves on cryogenic

tanks. Be suspicious of valves on cryogenic systems; the extremes of

temperature they undergo causes seals to fail frequently.

In the event a person is burned by a cryogen or material cooled to

cryogenic temperatures, the following first aid treatment should be given

pending the arrival and treatment of a physician or other medical care

worker:

If any cryogenic liquid contacts the skin or eyes, immediately flush

the affected area gently with tepid water (102°F

105°F, 38.9°C

40.5°C) and then apply cold compresses.

Applicable Hardware

General Precautions

Cryogen Safety

−

Foreword

Do not apply heat. Loosen any clothing that may restrict

circulation. Apply a sterile protective dressing to the affected area.

If the skin is blistered or there is any chance that the eyes have

been affected, get the patient immediately to a physici an for

treatment.

Containers of cryogenic liquids are self pressurizing (a s the liquid boils off,

vapor pressure increases). Hoses or lines used to transfer these liquids

should never be sealed at both ends (i.e. by closing valves at both ends).

When pouring cryogenic liquids from one container to another, the

receiving container should be cooled gradually to prevent damage by

thermal shock. The liquid should be poured slowly to avoid spattering due

to rapid boil off. The receiving vessel should be vent ed during the transfer.

Introduction of a substance at or near room temperature into a cryogenic

liquid should be done with great caution. There may be a violent gas boil

off and a considerable amount of splashing as a r esult of this rapid boi ling.

There is also a chance that the material may crack or catastrophically fail

due to forces caused by large diffe rences in ther mal contrac tion of differe nt

regions of the material. Personnel engaged in this type of activity should

be instructed concerning this hazard and should always wear a full face

shield and protective clothing. If severe spraying or splashing could occur,

safety glasses or chemical goggles along with body length protective

aprons will provide additional protection.

The properties of many materials at extremely low temperatures may be

quite different from the properties that these same materials exhibit at

room temperatures. Exercise extreme care when handling materials cooled

to cryogenic temperatures until the properties of these materials under

these conditions are known.

Metals to be used for use in cryogenic equipment application must posses

sufficient physical properties at these low temperatures. Since ordinary

carbon steels, and to somewhat a lesser extent, alloy steels, lose much of

their ductility at low temperature s, they are considered unsatisfactory and

sometimes unsafe for these applications. The austinetic Ni-Cr alloys

exhibit good ductility at these low temperatures and the most widely used

is 18-8 stainless steel. Copper, Monel

, brass and aluminum are also

considered satisfactory materials for cryogenic service .

Cryogenic storage systems are complex systems with the potential to

seriously injure personnel or equipment if not operated according to

procedures. Proper use of safety mechanisms (pressure relief valves,

Safety Summary

vii

Foreword

rupture disks, etc.) included in the cryostat and top plate assembly are

necessary.

First

Aid kit

Fire extinguisher rated for class C fires

Leather gloves

Face shield

Signs to indicate that there are potentially dangerous cryogens in

use in the area.

Instruction manual symbol: the product is marked with this

symbol when it is necessary for you to refer to the instruction

manual in order to protect against damage to the product or

personal injury.

Hazardous voltage symbol.

Alternating Current (Refer to IEC 417, No. 5032).

Off (Supply) (Refer to IEC 417, No. 5008).

On (Supply) (Refer to IEC 417, No. 5007).

The Warning sign denotes a hazard. It calls attention to a procedure or

practice, which if not correctly adhered to, could result in personal injury.

Do not proceed beyond a Warning sign until the indicated conditions are

fully understood and met.

The Caution sign denotes a hazard. It calls attention to an operating

procedure or practice, which if not adhered to, could cause damage or

destruction of a part or all of the product. Do not proceed beyond a Caution

sign until the indicated conditions are fully understood and met.

Safety Summary

Recommended Safety Equipment



Safety Legend

Warning

Caution

viii

1 Introduction

The American Magnetics, Inc. (AMI) Model 187 Liquid Level Controller

system (patent-pending) is an advanced, microprocessor-based solution

designed to provide compensated, capacitance-based level monitoring and

control of virtually any cryogenic liquid over a

wide range of operating

pressures and temperature s

The system consists of a Model 187 Liquid Level Controller, sensor,

connecting coaxial cables pairs, and an optional solenoid-oper ated fill

valve. The primary instrument sensing element is typically a 3/8 inch (9.5

mm) OD cylindrical capacitor constr ucted of stainless steel which allows a

non-conducting fluid to become the dielectric between the concentric

plates.

In addition to the primary cylindrical sensing element, circular-shaped

parallel plate capacitors are mounted on the sensing element in order to

provide “reference” data to compensate the primary capacitance

measurement. The instrument measures the primary sensing element

capacitance, compensates for any dielectric variations with respect to the

calibration conditions using the “reference” plates, and displays a level

reading. The sensors are nor mally constructed in o ne-piece lengths o f up to

20 feet (6.1 m).

The Model 187 is designed to be factory calibrated by AMI for a matched

sensor and is ready for immediate use upon delivery. The capacitance-

based primary and reference sensors provide f eedback to the instrument to

measure liquid level for any non-conducting liquid and compensate fo r a

wide range of operating conditions — therefore,

no user calibration

procedure is required

, but the Model 187 provides the option of a user

calibration

in addition to

the factory settings.

All calibration data is password protected to prevent unauthorized

modification and is stored in non-volatile memory. The instrument also

provides a function to select between the user calibration and the AMI

factory calibration.

1.1 Model 187 Features

1.1.1 Compensated capacitance-based level sensing

1.1.2 Factory calibration

Introduction

The instrument is equipped with a 16 x 2 backlit character-mode LCD

display which provides liquid level and setpoint indication in inches,

centimeters, or percent as selected by the user. A front panel keypad

interface allows the user to easily view and modify the instrument

settings. The default display indicates liquid level and fill/loss rate. The

current liquid level is updated and visible in many of the display modes

used in configuring various settings of the instrument.

The 4 x 4 keypad is provided for d irect entry of values f or se tpoints, sensor

lengths, and other functions. The keyp ad also provide s a con ve nient me nu-

type interface for configuring various instrument se ttings that require

selection from a list of options.

The Model 187 provides four level setpoints, two of which (A & B) are

control setpoints used to control liquid level through use of a solenoid-

operated fill valve. The remaining setpoi nts (HI & LO) are ala rm setpoints

and can be set for other control or alarm functions.

The HI and LO setpoints operate relay contacts in addition to the front

panel LED indications. LED indication is also provided for the A setpoint,

B setpoint, and automatic contro ller (FILL) f unction of t he instrument. All

setpoints are accessible via the keypad. The automatic controller (FILL)

function can also be manually overridden or disabled using the keypad.

A timeout feature is also provided with the automatic controller (FILL)

function. The timeout specifies the maximum amount of time necessary for

the Model 187 to fill the target vessel to the A setpoint. If fill is not

achieved within the timeout period, the Model 187 ends the fill operation

(de-energizes the rear panel controller output) and indicates expiration of

the timeout feature by blinking t he FILL LED and set ting the approp riate

flags accessible through the serial or GPIB remote interfaces.

The Model 187 can be configured to provide an optional analog 0-10 volt

DC signal accessible from the rear panel of the instrument for use with a

recorder. A 4-20 mA current loop option is available in lieu of the voltage

signal.

RS-232 is provided as a standard digital interface for the Model 187.

Additional digital interface options, including RS-422 or GPIB (IEEE

488.2 compliant), are available. The serial and GPIB remote interfaces

provide a comprehensive command set for monitoring and configuring all

functions of the instrument.

Model 187 Features

1.1.3 Convenient display and direct keypad entry

1.1.4 Automatic level control

1.1.5 Remote computer monitoring or controlled operation

Introduction

237,21

Front Panel Layout

1.2 Front Panel Layout

/HYHO  PLQ 

32:(5

$0,

2))

16 character x 2 line LCD display

with backlight

$0,

0RGHO 

/LTXLG /HYHO

&RQWUROOHU

+, $ % /2 ),//

 Ã+, Ã/2

 Ã% Ã5$7(  Ã /(1

 Ã ),// Ã087( Ã&200

 Ã &$/

HI, A, B, and LO alarm LEDs



 Ã$

81,76 (17(5

(6&

0(18

4 x 4 keypad

Powe r switc h

FILL Indicator LED

Introduction

Rear Panel Layout

1.3 Rear Panel Layout

1 3

*$6 5() /,4 5() 352%( *$6 5() /,4 5() 352%(

$0(5,&$1 0$*1(7,&6 ,1& 2$. 5,'*( 71 86$

2873876 ,13876

- - - - - -

56

- -

4 6

5 7

&21752//(5 287387



/,1( 92/7$*( $ 0$;

- ,(((

/,1(  +] $ 0$;

 9  9

6(/(&725 6:,7&+ ,16,'(

BNC

coaxial connector outputs

to sensor

BNC

coaxial connector inputs

from sensor IEEE-488 communications port

RS-232 (standard) or RS-422

DB-9 female connector

Controller output receptacle

(reverse IEC-320) IEC-320 Power cord connector

(IEC-320)

Auxiliary DB-9 male connector

(see

Appendix

for pinout)

Introduction

Instrument/Sensor System Diagram

1.4 System Diagram

SENSOR CABLES RG-59/U COAXIAL 150 FEET MAXIMUM LENGTH

MAXIMUM

MEASURED

SPAN

VAPOR REFERENCE PLATE CAPACITOR

CONCENTRIC-TUBE, CAPACITANCE-BASED PROBE

2873876 ,13876

*$6 5() /,4 5() 352%( *$6 5() /,4 5() 352%(

- - - - - -

$0(5,&$1 0$*1(7,&6 ,1& 2$. 5,'*( 7186$

- -

56

&21752//(5 287387



/,1( 92/7$*( $0$;

REAR PANEL

SOLENOID-OPERATED FLOW VALVE (OPTIONAL)

/HYHO  

PLQ 

32:(5

$0,

0RGHO 

/LTXLG /HYHO

2))

&RQWUROOHU

FRONT PANEL

LIQUID LEVEL CONTROLLER

 Ã+, Ã/2

Ã% Ã5$7( Ã /(1

 Ã ),// Ã087( Ã&200 +, $ %

 Ã &$/ /2

),//

MODEL 187

- ,(((

/,1(  +]$ 0$;

 9  9

6(/(&725 6:,7&+ ,16,'(

(6&

 Ã$

0(18

237,21



81,76 (17(5

MINIMUM

ZERO

OFFSET

Figure 1-1.

LIQUID REFERENCE PLATE CAPACITOR

Model 187 instrument, control valve, and sensor system diagram.

Introduction

Specifications

1.5 Model 187 Specifications @ 25 °C

Level Measurements

Resolution: 0.1 %, 0.1 cm, or 0.1 in

Accuracy:

Linearity:

Temperature Coefficient: 0.1% / °C

Operating Parameters

HI, A, B, and LO Alarms:

HI/LO Alarm Relay Contact Ratings: 10 V at 0.5 A (normally open, closed on alarm)

Controller Output: AC line voltage @ 2A max current

Fill Timer: 0.1 to 9,999.9 minutes

Analog Output

Integral Non-linearit y:

Resolution: 16 bits Total Error:

Current Drift (4-20 mA): 75 ppm / °C

Voltage Drift (0-10 V): 100 ppm / °C

0.5%

0.2%

% to 100% adjustable

0.012%

0.25% for 4-20 mA output

0.5% for 0-10 V output

Power Requirements

Memory Backup Battery: 3.6 Volt AA Lithium Cell

Physical

Dimensions (Standard): 97 mm H x 213 mm W x 290 mm D

Weight (Standard): 2.0 kg (5.4 lbs.)

Dimensions (Rack Mount): 89 mm H x 483 mm W x 290 mm D

Weight (Rack Mount): 2.3 kg (6.1 lbs.)

Environmental

Ambient Temperature: Operating: 0 °C to 50 °C (32 °F to 122 °F)

Relative Humidity: 0% to 95%; non-condensing

Primary: 100-120 or 200-240 VAC ±10%

50 - 60 Hz, 2.2 A max

(3.8" H x 8.4" W x 11.4" D)

(3.5" H x 19" W x 11.4" D)

Nonoperating: −20 °C to 60 °C (−4 °F to 140 °F)

2 Installation

Before energizing the instrument, the earth ground of the power

receptacle must be verified to be at earth potential and able to carry

the rated current of the power circuit. Using extension cords should

be avoided; however, if one must be used, ensure the ground

conductor is intact and capable of carrying the rated current.

In the event that the ground path of the instrument becomes less

than sufficient to ca r ry th e ra te d curr e n t of the po w e r ci r cu i t, th e

instrument should be disconnected from power, labeled as unsafe,

and removed from place of operation.

Do not operate this instrument in the presence of flammable gases.

Doing so could result in a life-threatening explosion.

Do not modify this instrument in any way. If component

replacement is required, return the instrument to AMI facilities as

described in the Troubleshooting section of this manual.

Carefully remove the instrument, sensor, and interconnecting coaxial

cables from the shipping carto n and remove al l packaging material . A rack

mounting kit is supplied if the instrument was purchased with the rack

mount option.

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.

If the chassis is a table top model, place the instrument on a flat, secure

surface.

Warning

2.1 Unpacking the Instrument

Note

Installation

If the

instrument has a rack mount chassis, follow the following procedure:

Attach the rack mount adapter pieces to the inst rument by fir st

removing the four screws on the side of the instrument that

attach the cover to the chassis. Attach the rack mount adapter

pieces to the sides of the instrument by reinstalling the screws.

Install the instrument in a 19" rack by securing the front panel

to the rail in each of the four corners with mounting hardware

supplied by the cabinet manufacturer.

Do not remove the cabinet feet and then rei n sert the origi n al screws.

Doing so could present a severe life-threatening electrical hazard. If

removal of the cabinet feet is desired, replace the original screws

with screws not to exceed 1/4" in length. Screws longer than 1/4"

will contact and damage the printed circuit board inside the unit.

Exercise care

when installing the

sensor since dents, crimps, bends or

other physical distortions in the

cylindrical and plate sensors will

change electrical characteristics

and possibly cause calibration

errors and/or disruption of proper

instrument operation. It is also

important to ensure that the sensor

is installed in a vertical orientation

for optimal operation of the sensors.

Make a note of the 0% and 100%

points of the target vessel per

diagram at left. Before installing

the sensor and before filling the

target vessel, the user may first

want to review the

Operation

section—especially the zero offset

and measured span length settings

discussed on page 14.

Drawings will be provided for

custom sensor or mounting flange

designs.

Installing the sensor

2.2 Rack Mounting the Instrument

Warning

2.3 Installing the Sensor

100%

MAXIMUM

MEASURED

SPAN

MINIMUM

ZERO

OFFSET

Installation

The electrical char acteristics of the interconnecting coaxial cables

are temperature dependent over extreme ranges and the cables may

become brittle at cryo genic temperatures. The ca bles should be

mounted in such a manner as to avoid large temperature gradients

such as those encountered in the pa th of dewar vents.

Operation of the AMI Model 187 Liquid Level Instrument with a

device other than an AMI Liquid Level Sensor may void the

instrument warranty.

Connect

the Model 187 to the sensor using the six supplied RG-59/U

coaxial cables. Ensure the cables are connected to the correct sensor and

instrument

BNC connecto

r (see Figure 2-1 below and page 5 for a system

diagram). The numbers shown in Figure 2-1 will be metal-stamped on the

sensor top-plate and probe cable adapter.

Moisture or contaminants in any of the BNC coaxial connectors can

short the measu r ement and cause er roneous read in gs . A pack of

non-conductive electrical connection lubricant (ECL) has been

Connecting the sensor cables

2.4 Connecting the Model 187 to the Sensor

Note

Caution

CONNECT 3 TO OUTPUTS: PROBE (J3) CONNECT 6 TO INPUTS: PROBE (J6)

3 6

CONNECT TO

CENTER BNC CONNECTOR

CONNECT 5 TO INPUTS: LIQ REF (J5)

Figure 2-1.

Diagram of sensor top-plate and cable connections.

CONNECT 1 TO OUTPUTS: GAS REF (J1)

CONNECT 4 TO INPUTS: GAS REF (J4)CONNECT 2 TO OUTPUTS: LIQ REF (J2)

Caution

Installation

included with the liquid level sensor packaging to reduce the

possibility of this occurring. If the sensor is operated in an

environment where it will be exposed to moisture or other

contaminants, AMI recommends applying a small amount of ECL to

any of the BNC connectors that may be exposed. Mate the doped

connectors and then remove any ex cess ECL from the outside of the

connector. Added protection can be achieved by coveri ng the doped

connections with a short section of heat-shrink tubing.

Install the

solenoid-operated fill valve by connecti ng the valve power cable

to the AC controller output rec ept acle on the rear pan el of t he ins tru ment.

The standard AMI supplied valve has a 9/32 inch orifice and the input and

output are tapped for 3/8 NPT.

When using a solenoid-operated control valve with the Model 187,

ensure the valve is configured for the opera ting voltage of the Model

187. Failure to do so will result in faulty operation and may al so

result in valve dam age .

Before touching any of the controller output receptacle terminals or

touching the wiring connected to these terminals, remove power to

the instrument by unplugging it or turning the power switch to the

off position .

The controller output recep tacle conduc ts hazardous AC line volta ge

potentials. It is for use with equipment which has no live parts

which are accessible. Conductors connected to its terminals must be

insulated from user contact by reinforced or double insulation

capable of withstanding 4250 V (impulse) for a 230 VAC Category II

installation, or 2550 V (impulse) for a 120 VAC Category II

installation.

This instrument is designed for opera tion from a single-ph ase powe r

source for maximum safety. The controller output receptacle

circuitry only switches the “line” (“ hot”) connection to the AC mains.

If two-phase power is applied, any equipment connected to the

controller output receptacle conducts hazardous AC voltage even

when the controller output receptacle is not energized.

Connecting the sensor cables

2.5 Installing the Optional Solenoid-Operated Fill Valve

Caution

Warning

1. MSDS sheets for the ECL are available upon request.

Installation

The Model 187

operates on 50-60 Hz power and may be configured

for 100-120 or 200-240 VAC ±10 %. The power requirements fo r each

instrument is marked on the calibration sticker on the bottom of the

instrument. Verify that your instrument is configured for your

power source prior to pl ugging in the li ne cord. Do not f ail to connect

the input ground terminal securely to an external earth ground.

Verify that th e

instrument is configured for the proper operating voltage

by referring to the calibration sticker affixed to the bott om of the

instrument. If the operating voltage is correct, plug the line cord into the

appropriate power receptacle.

If the instrument operating voltage needs to be changed, ensure the

instrument is de-energized by disconnecting the power cord from the

power source. Remove the instrum ent cover and slide the voltage selector

switch on the main printed circuit board to the proper volt age. Replace the

instrument cover.

Verifying power requirements

2.6 Connecting the Instrument to Power

Warning

Installation

Verifying power requirements

+ 52 hidden pages