NEAR-SURFACE STRAINMETERS AT SITES ALONG THE SAN ANDREAS FAULT, CALIFORNIA ...

94 Pages·2011·8.05 MB·English

UNITED STATES DEPARTMENT OF THE INTERIOR
GEOLOGICAL SURVEY
NEAR-SURFACE STRAINMETERS AT SITES ALONG THE SAN ANDREAS FAULT, CALIFORNIA:
INSTALLATION, OPERATION AND MAINTENANCE.
by
Alan C. Jones and M. J. S. Johns ton
Open-File Report 95-487
This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey edi
torial standards. Any use of trade names, product, or firm is for descriptive purposes only and does not
imply endorsement by the U.S. Government.
1995
CONTENTS
1. Introduction .................................................................................................................................... 3
1.1. Historical Background ...................................................................................................... 3
2. Instrument Description ................................................................................................................... 5
2.1 Transducers ......................................................................................................................... 6
2.2. Instrument Assembly ......................................................................................................... 6
3. Site Selection and Preparation ....................................................................................................... 8
3.1. Field Assembly .................................................................................................................. 12
4. Electronics ...................................................................................................................................... 14
4.1 Description .......................................................................................................................... 14
4.2. Power Supply .................................................................................................................... 17
5. Strainmeter Field Maintenance ...................................................................................................... 17
5.1. Field Visit .......................................................................................................................... 17
5.2. Rustrak Recorders ............................................................................................................. 19
6. Data Telemetry System .................................................................................................................. 20
6.1. DCP Programming ............................................................................................................ 20
7. Acknowledgments .......................................................................................................................... 23
8. References ...................................................................................................................................... 23
9. Appendix ........................................................................................................................................ 24
9.0 Figures - Construction ........................................................................................................ 24
9.1 Strainmeter Plug Connector ............................................................................................... 44
9.2 Strainmeter Electronics Schematics .................................................................................. 45
9.3 DIAX Extensometer ........................................................................................................... 51
9.4 Singer Ratio Transformer .................................................................................................. 58
9.5 Nonshrink Grout ................................................................................................................. 78
9.6 Instrument Boxes ................................................................................................................ 81
9.7 Rustrak Recorder ................................................................................................................ 83
10. Data, Long Term Plots ................................................................................................................ 91
TABLE OF CONTENTS
SECTION PAGE
I General Description ............... 1-1
II Operating Instructions .............. 2-1
III Theory of Operation ............... 3-1
IV Maintenance ................... 4-1
V Calibration ................... 5-1
VI Parts List .................... 6-1
RatioTran Engineering Bulletins ......... A-l
LIST OF TABLES
TABLE PAGE
1-1 Specifications .................. 1-2
5-1 List of Test Equipment .............. 5-2
5-2 Calibration Tolerances .............. 5-3
LIST OF ILLUSTRATIONS
FIGURE PAGE
1-1 Model RT-60 RatioTran ............. 1-1
1-2 Dimensions ................... 1-2
2-1 Typical Application ............... 2-1
2-2 Cascade Output Connections ........... 2-2
3-1 Typical Schematic ................ 3-1
5-1 Impedance Test Setup .............. 5-1
5-2 Ratio Accuracy Test ............... 5-2
iii/iv
Description Summary
Description......................................................... 1
Installation........................................................ 2
Wiring................................................................. 3
Loading Instructions........................................... 4 & 5
Operating Instructions........................................ 6
Calibration.......................................................... 6
Model 2194 Special Instructions......................... 7
Changing Scales and Windows ............................ 8
Basic ranges of DC recorders............................... 9
Chart paper........................................................ 10
The Rustrak DC* recorder prints through the impinging Changing Gear Trains (Boxes).............................11
action of its stylus driven by the chopper bar against pres
Cleaning Your Recorder..................................... 9
sure-sensitive chart paper. Its presentation is a series of dots
Formulas............................................................ 9
appearing as a continuous line.
Gear Box ratios ................................................. 9
Recording on the chord of the stylus arc by the edge of
Chart speed table................................................ 9
the chopper bar is possible with a stylus able to write along
Writing speed table............................................. 9
its length rather than its point. This results in chart paper
printed with straight lines and rectilinear recordings. Trace Density table............................................ 9
Writing speed varies with motor speed. Chart speed and F204 Controller ................................................ 10
trace density depend on the ratio of the interchangeable Features & Accessories.......................................11
gear box which couples the paper drive to the motor. Troubleshooting & Repair..................................12
Exploded View...................................................Back Cover
*DC Recorders are intended to record DC parameters such as voltage "200" Series Template.......................................Back Cover
or current. The chart drive motor may operate from AC lines or be
battery-operated without changing the DC designation.
Installation
3/16x5/16 SLOT
MTG
MODELS 288, 291, 2146 & 2194: 1-13/16
-» *- 1-5/16
These recorders can be panel-mounted or used as table-top
. \
portable instruments. Hardware is furnished for both pur » « 13/16
poses. H \
1-13/16 \ I
3/8
1
Portable: JL.?>- 6 f e} 5/Jj' |
Install four (4) rubber feet in tapped holes at bottom of i
case using four (4) 4-40 x 1/4" screws provided. Snap white T = t, I / ^ i.
plastic cardholder into holes at top of case. CASE DEPTH:
^
.>
L'.'. 288 4-5/16"
Panel-Mounting: r» *r' 291 4-5/16"
to 2194 6
Follow instructions on drawing included with hardware 63IB iI if" ' ? F137 4-5/16"
kit. Mount both brackets to recorder and make panel cutout LT > ^« FF221074 67 -11/16" rjr/v1
to size required or use Model 2176precut panels. See record F109 4-5/16"
er outline. For custom mounting, see template on back v>-'- 'v V^V *v* r*,ls-.i''% - '.- 'v*> , -' -"«.V >'" '*? . t TX;<J^l' <* i*;?»^^5*;.l'' W F 1A 4-5/16"
cover. If mounting with Model 2196 escutcheon, do not drill . '-.<t? '.«<:- ,>-i i'V-ir--v/, ! ",^^;^ ^
.J^
holes in panel and follow special instructions furnished with -- !-.. ' .^_ -..<- ', '«< !! 1 I-rCj'lj_ 0 __ " J
bezel. i ^D mtt) _ _ _ G _ B - 5/8
5/16*-! i) 4-5/16 » -1-1/16
300 SERIES MODELS: 11/16+- *h- 2-1/4 H
Normally the 300 series recorder is shipped with rubber «- 3-5/8 » H« _..,._ « ^
feet and handle mounted at the factory. It is ready to use as
received. However, a modification kit is available for panel-
mounting without drilling holes in the case.
Wiring tviooei
Plug connections and terminals are identified on a label
inside your recorder. Refer to this d?ta for correct wiring.
100 n 1 where
RI *iunt minor
SCHEMATICS n factor
(1CXX)V|,) I00>*here
Model 288 Vf, Volts full «caie
100 * Internal R o1 mtirr
300 SERIES.
Since a "300 Series" recorder is a tandem unit enclosing
two basic "200 Series" instruments, the inner wiring para
llels the preceding schematics. Terminals are barrier strips
Terminal Connections with connections as follows:
PIN H MODEL 288 MODEL 291 MODEL 2146 TERM * 8 I 7 6 1 5 - I 3 2 1
1 Galvo + G»lvo 1 + Galvo + Model 388 NOT USED
Gaivo 2 Galvo 1
2 Galvo - Calvo 1 - G»lvo -
Model 391
3 Motor (DC-0 Motor (DC-0 Motor (DC+) Galvo 4 Galvo 3 Galvo 2 Galvo 1
4 Motor (1) Motor (1) Motor (1) Model 3146 Event Event
5 Ground (21 (31 Galvo 2 + Actuator Actuator 2 Gaivo 2 Actuator 1 Galvo 1
Other Set right Right center Let! Center See i-ft
6 (21 Galvo 2 - Actuator Models Scale Scale Factor Scale Factor Scale
(1) DC Motors are polarized Positive terminal is ilwdys pm 3
(21 Pins 5 & 6 ere additional ranges in multi rang* recorders
AC line cords terminate in three-prong plugs for 117 VAC.
(3) If all pins are used, ground to chassis plug jcrew
Use grounded outlet. Do not defeat purpose of grounding
Model 2146 plug.
DC line cords terminate in a red (+) wire, a black {-) wire and
a green lead connected to case ground. Ground this wire
when using recorder.
Actuator Solenoid. 24 VDC @ 70 MA Standard
Loading Instructions SUPPLY ROLLER
KETAINIKH3
REROLLMODE CLIPS
(USE FRESH ROLL
OF CHART PAPER
AT EACH LOADING)
TAPE
THUMBSCREW
1. OPEN RECORDER. UNLATCH RETAINING CLIPS. SLIDE CARDBOARD SLEEVE ONTO TAKE-UP ROLL
OPEN CHASSIS LATCH. REMOVESUPPLY AND TAKE- ER. BUTT PAPER AGAINST DISC AND TAPE END OF
UP ROLLERS CHART PAPER TOSLEEVE. TURN ONE RE VOLUTION
FOR PROPER PAPER ALIGNMENT.
SLIDE SUPPLY ROLLER INTO FULL ROLL OF CHART
ROLL PAPER TIGHTLY AND STRAIGHT ON TAKfc-UP
PAPER, ROLLER SHOULDER NEAREST PAPER PER
ROLLER. KEEP PAPER TAUT. DROP INTO DEEPER
^ORATIONS UNROLL ABOUT A FOOT AND SLIDE
NOTCH, ENGAGING GEAR. CLOSE RETAINING
PAPER (BACK SIDE UP) BETWEEN SIDE PLATE AND
LATCH STEER PAPER AGAINST DRUM TO CLEAR CLIPS SNAP UP CHASSIS LATCH. CLOSE RECORDER
POINTER. ENGAGE PAPER PERFORATIONS INTO ADVANCE PAPER BY DEPRESSING AND TURNING
DRUM SPROCKETS AND DROP ROLL INTO SEATING CHART ADVANCE WHEEL ON FRONT PANEL
NOTCHES
SUPPLY ROLL
ENGAGE
SEAR
LATCH
SIDE PLATE
TEAR-OFF MODE
THROUGH BELTS. SEAT
(USE PARTIAL OR FULL ROLLER TO ENGAGE
DRIVE GEAR. PULL
ROLLS OF CHART PAPER)
BELTS INTO CHAMFER-
EDCENTER GROOVE OF
1. SNAP OUT NAMEPLATE USING GUIDE ROLLER AND
SCREWDRIVER.REMOVE 2BELTS. ALIGN INTO V-SLOTSON
REPLACE NAMEPLATE. TAKE-UP ROLLER. IN
SERT SUPPLY ROLLER
INTO SPOOL OF CHART
PAPER (MAY BE PAR
LATCH
TIAL ROLL) SO ROLLER
SHOULDER IS NEAREST
PERFORATIONS. UNROLL CHART PAPER AND-SLIDE
(BACK SIDE UP) BETWEEN SIDE PLATE AND LATCH.
ENGAGE PAPER PERFORATIONS INTO DRUM SPROCK
JTS AND DROP ROLL INTO SEATING NOTCHES.______
. CLOSE RETAINING CLIPS. SNAP UP CHASSIS LATCH.
PULL DRIVE BELTS INTO V SLOTS ON GUIDE ROLL
ER. CLOSE RECORDER.
LATCH
SUPPLY ROLL
SIDE PLATE
RELEASE SCftEW
2 OPEN RECORDER. UNLATCH RETAINING CLIPS.
OPEN CHASSIS LATCH. REMOVE SUPPLY AND TAKE-
UP ROLLERS. UNSCREW RELEASE SCREW 2 OR 3
TURNS.SPRINGSIDE PLATE. REMOVEGUIDE ROLL
ER. SLIP ROLLER THROUGH 2 BELTS. RESEAT
ROLLER TIGHTEN RELEASE SCREW.
TO TOP SLOTS GUIDE ROLLER
OF RECORDER
CONVERSION INFORMATION
REROLL TO TEAR-OFF (use* drive belts)
Remove cardboard sleeve from take-up roller. Proceed
with tear-off loading instructions. ADVANCE PAPER AND SET TIME BY DEPRESSING
TEAR-OFF TO REROLL (Uses cardboard sleeve) AND TURNING CHART ADVANCE WHEEL. TEAR
OFF PAPER AS NEEDED.
Store drive belts under front nameplate. Replace guide
roller and finger tighten knurled release screw. Continue
with reroll loading instructions.
Operating Instructions
Calibration: (All Models Except 2194)
MODELS 288, 291, 2146, 300 SERIES No calibration except for periodic adjustment of the
mechanical zero is needed on Rustrak DC recorders.
1. Install recorder and wire as detailed on page 3.
2. Load chart paper as shown on pages 4 & 5.
Mechanical Zero:
3. Apply power to motor and zero trace if needed.
4. Feed in signal to be recorded. If trace on chart paper is above or below zero with gal
5. Recorder can operate unattended until chart paper sup vanometer terminals shorted and motor running, snap out
ply is depleted. front nameplate (using fine screwdriver in slot at left) and
vary zero adjust screw.
(Event Marker), Model 2146 The stylus also may be adjusted mechanically at any
point upscale if the recorder is used over a narrow span of
1. Wire actuator in series with contact switch and DC
the calibrated scale. Calibrate against a standard meter across
power source (Check voltage rating of actuator). See
the galvo terminals and a source.
schematic.
See page 7 for special instructions on Model 2194.
' 2. Chart paper speed depends on gear train and motor com
bination selected for analog channel.
3. Recorder will print pulse for every change in state of MODEL 2194:
ioof>
contact switch.
soon
BAL
- == 800u.fd
3V
SWITCH ,
l_ __ __ __ J
Wiring to actuator of model 2146 Actuator responds to state of
SPST switch.
The full-scale sensitivity of 1 microampere (rang* 0-10 mV) Is TEAR-OFF or REROLL. Operating mode Is quickly changed from
achieved with a medium gain amplifier driving a 100 mV meter. one to the other In the field. Reroll generally used for long runs
Input Impedance is 10,000 ohms and the recorder is intended for a t«ar-off feature allows sections of chart to be removed for Im
maximum source Impedance of 100 ohms. Error due to amplifier
mediate analysis and filing.
loading with a 100 ohm source Is less than 1% but rises to about
10% with a IK ohm source. Temperature drift is also propor-
tiona ely higher.
Electrical Zero: ACCESS WINDOW. Slides down for notes.
1. With power off, adjust mechanical zero (behind front name-
plate) until stylus (at chopper bar level) is at zero on chart paper.
2. AHow Vz hour warmup with power on.
3. Short Input terminals and adjust ZERO (on case rear) for zero NAMEPLATE. Conceals mechanical meter zero adjustment and
on chart paper. storage for tear-off feature drive belts. Snap out with fine screw
-4. Remove short and adjust BALance (on case rear) for zero trace. driver.
Short terminals again. Reading should not change from open to
shorted condition.
5. If any change occurs, repeat steps 3 and 4.
Calibration: CHART ADVANCE FEATURE. Push In and roll down thumb
1. Zero the recorder as shown in Electrical Zero Instructions. wheel to advance chart for tear-off or to set time on chart.
2. Apply 10 mV signal to binding posts from generator whose out
put resistance is less than 100 ohms.
3. Adjust CAL control (case rear) for full-scale printout.
Increasing Current Range:
QUICK REVIEW FEATURE. Recorded chart can be unrolled for
To increase range (reduce current sensitivity), a shunt at the In
analysis. Lift left retaining clip and set roll into closer notch. Un
put terminals equal to 10,000/n-l may be used. For example, a
full-scale sensitivity of 100 uA is achieved with a 101 ohm resistor roll as needed. Rewind chart with thumbwheel then reseat roller
while a 0.01 ohm resistor results in 1 Amp full-scale readings. Into deeper notch. Lock retaining clip.
£xpanding Voltage Range:
The 2194 can be made into a solid-state voltmeter with 100,000
ohms/volt sensitivity by using a series multiplier whose value in
ohms equals 100,000 Vfs - 1000 (where Vfs equals volts full-scale) INTERCHANGEABLE GEAR TRAINS. Provide easy change of
providing a IK ohm resistor shunts the input of the recorder. chart speed.
Representative values are IK ohm for a 10 mV range, 99K ohms for
1 volt full-scale and 1 Megohm for a 10 V. scale. The IK resistor
should be wired to the recorder directly at the binding posts before
connecting the multiplier.
Caution:
Voltages In excess of 1 VDC at the input may damage the
amplifier.
ij
1. SLIDE DOWN ACCESS WINDOW.
2 GRASP PLASTIC BEZEL AT POINT 300 SERIES
"X"ANDPULLOUT AWAVFROMRE-
CORDER, FOUR TABS ALONG SIDES HOWTO CHANGE SCALE AND/OR ACCESS WINDOW
WILL RELEASE. NO TOOLS ARE
NEEDED. 1. Slide down top access window and bow it towards you until it
3. REMOVE ACCESS WINDOW (TWO
PIECES) AND SCALE releases
4 DROP IN NEW SCA^E. 2. Open recorder and remove 4-40 Pan Head screw holding Quick
5. REPLACE ACCESS WINDOW LOWER Review Thumbwheel arm to panel.
WINDOW HAS TWO DOMED PRO
JECTIONS FACING TOWARDS AND
CLAMPING AGAINST SCALE. 3 Remove two 4-40 Pan Head screws from rear of bezel Lefthand
6 FIT PLASTIC BEZEL IN PLACE, BOT screw is accessible after removing Quick Review Thumbwheel
TOM IN FIRST.FLEX TOP OF BEZEL.
INSERT TABS ON SIDE OF THUMB whiie right hand screw is unobstructed.
1 WHEEL, THEN DROP IN TABS ON
RIGHT. 4. Lift out white bezel and anodized spacer.
7. SLIDE UP ACCESS WINDOW. IF
LOWER WINDOW IS REVERSED, UP 5. Remove lower access window and change scale. Scale may be
PER WINDOW WILL NOT SLIDE affixed with double-gummed tape so remove with care.
DOWN COMPLETELY.
6. Replace lower access window in cutout.
200 SERIES
7. Drop anodized spacer into panel then white bezel, inserting lower
tabs first. Replace two 4-40 Pan Head screws and tighten se
curely.
8 Close recorder
HOW TO CHANGE SCALE
9. Bow out top access window towards you anci insert both ends
AND/OR WINDOW
into bezel slot Slide window into place
t VIIIH4U4J
The coating used on Rustrak recorders is Nextel Brand WRITING SPEED (strikes/sec.) - motor speed (rpm)
Suede Coating by 3M. It was chosen because of its tough 4
CHART SPEED (in./hr.) - motor speed (rpm)x gear train assembly number
ness and visual qualities.
It can be cleaned with a damp sponge. The usual house TRACE DENSITY (r.-kes/in.) -_______1800______
hold spray and liquid cleaners can be used on tough stains Bear train assembly number
DURATION OF ROLL 'in hrs.)=______756
without damage to the coating.
chart speed (m./hr.)
Gear Train Ratiost Chart Speed, Writing Speed and Trace Density Table
oMDrROx«ITViOER WSPREIETDING 41*0/8 1 214/04 1 1120/ 21 «01 1 X2 1 203 1 IS4 1 160 1 61 01 1S 21 14 51 32 01 I4S5 1 6i 0t GGEEAARR TTRRAAIINN NROATIO
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TRACE DENSITY 14400 7200 360C 1800 900 too 450 300 ISO ISO 120 60 40 30 STRIKES PER INCH (DENSITY)
2 Adjust controller setpomt knob until relay (de) actuates
f204 Controller Loading on the'galvanometer, because the input imped Swing knob back and forth Only slight movement of
anceof the op amp is about 30 megohms, is limited to about
knob should be possible between on and off
0.2 microamperes
Relay contacts are rated 5 amps, resistive load, at 30 VDC 3 With galvo at center scale and reference pot at the con
or 115 VAC The "normally open" and "normally-closed" trol pomt the knob should be at the center mark on its
contacts can be adapted to almost any application whose dial If not. loosen set screw and move pointer to center
functions lend themselves to on-off control mark
Configurations (A or B) represent control direction The 4 Check knob po.nter against scale at 0. 20, 40 60 and 100
A style closes the normally open contact below the setpomt percent points A deviation of one division at any point
and opens it above is acceptable
Style B configuration closes relay contacts above the set
point and opens them below
Besides these simple styles, two setpomt controllers are
available Style AA, featuring two control amplifiers both
actuating the relay below the setpomt. are useful for control
at one point and shut-down or alarming at the other
Style AB is useful m "go-no-go" applications, or. "low
Millnmelefi «nd microammeters are basicallv low range
vo(1 metefi which registef voltage «xcur$ion» at their termi in-high" type of information needs Similar applications as
nals. Th«e minute fluctuations represent a real change in with style AA are possible with the BB configuration but
tt* monitored circuit and c«n be used to control circuit with control above the setpomt
quantities That's the function of the F204 On Off Control No controller is limned to its initial configuration since
styles can be changed by the user
tlrearn TFsheiseat oturfr 2ein0 4s eriise s aw ictohm a praerlaayto rS PaOmTp lcifoienrt acdtrsiv einnga bl*e oponw-oefrf penTdhse o nty gpael voa1n osmeetpteorm ct onwnheectthioenr s lorewla t(iAve) otor thhiegh r e(fBer)e, ndcee Chart Paper
control of parameters being recorded or the external wiring voltage Since the relay energizes only when the positive ter
Umgaey ebxec uardsaiopntesd a t toth eo pgeanlv aonr ocmloestee r atneyr mciinrcaulsi t Btoy fcoolmlopwa rvinolg pmomssaiib loe f ttoh ec hoapn gaem pse itsp momori e typpoessit ivbey trheavne rtshineg- tecromninneacl,ti oitn sis Rustrak recorders use pressure-sensitive chart paper in
voltage levels of the meter terminals with a stable reference to the galvo 63-foot rolls (one month's recording at 1 inch/hour)
voltage adjustable from the front panel, limits can be set for These connections are jumpers on the controller circuit
board mounted on the case rear The (umpers are located at MODELS 288 and 2194
the relay twitching function
Both the reference voltage and the voltage impressed ac trw bxottom o.f thex PC boar.d in xthis sequ.encex. Usually Style A. 50 divisions, 2-9/16" wide, useable
rots the mete* terminals are applied to the inputs of an width. 2-5/16". (Also styles B. C, G, H. I. K and L.)
operational amplifier
The operational amplifier in the F204 is operated open
MODEL 291:
toop, that is, with no feedback Its voltage gam including
the power stage driving relay K1, is about 125,000 or 02 Cnss cross or "X" lumpers denote an "A" type configu Style D. 20 divisions or Style F, 15 divisions per chan
millivolts at the input give 24 volts out ration while parallel III) jumpers result m a "B" configura nel Each 2-9/16" wide useable width, 1" per channel
Voltage across the galvo is applied to the positive input tion
PI is the front panel setpomt adiustment that vanes the re To change setpoml types remove four screws holding MODEL 2146
iereWnchee nv otlhtaeg ev oalptapgliee d ot1o tthhee npeogsaittiivvee ininppuutt terminal (the cthaese rereaar r paton erle cWohrdeenr sHoolduesriningg , Tbhee cna urenfsucl renwot PtCo bdoeasrtrdo yfr othme Uses Style N paper, 29/16' wide, useable 2" (Analog)
gjivo input I is below or equal to the voltage at the negative printed circuit board & 1/2" (Event)
terminal (the reference), Ol is cut oft ana K1 de energ^ed
If the positive terminal becomes more positive than the - ADJUSTING PANEL KNOBS 300 Series
terminal by more than about 02 millivolts (resolution) Q1 See 300 Series catalog for many available styles
1 Apply signal to galvanometer lor center scale reading
conducts and energizes K 1
F109A, SELECTIVE COMMAND PRINT: Recorders with this feature print two traces on the chart
with only one galvanometer. Inputs are switched through a
Recorders with this feature have a solenoid-actuated
striker rather than one which operates from the motor cam. motor cam to proouce two indrpendent traces identified by
a regular break in one recording. A Model 288/F137 can
(There is no cam). No recording occurs until the solenoid is
en rgized and the striker presses the stylus against the paper monitor two signals while a 291-T137 is a four-channel re
corder.
until released by the solenoid. Average duty cycle must not
exceed 25 percent.
WIRING; MODEL 288:
Connections are made through two binding posts on the
case rear. They are labeled for correct voltages. The second channel input is wired to pins 5 & 6 of the
chassis plug. Other models use binding posts on the case rear.
F109B, AUTOMATIC COMMAND PRINT: Check the label inside your recorder for correct wiring.
This feature retains the cam-operated striker but the
SPEED LIMITATIONS:
motor cam doesn't engage until the solenoid is energized.
Recorder operates normally as long as solenoid is actuated. Because of the extra cam, limitations in chart and writ
Duty cycle can be up to 100%. ing speed are inherent with the F137. Maximum motor speed
Connections to solenoid are made through binding posts is 1 rpm and only gear boxes #1/8 to #12 can be used in the
labeled for correct voltages. recorder.
F1A, QUIET FEATURE: 111 & 881:
The Quiet Feature reduces impact noise t>f the striker by Switchable shunts and multipliers as also hi-current shunts
changing the writing method to a pressing action. This is a are available for Models 288 and 291. Separate instructions
mechanical feature only. The F1A is functional with all accompany these accessories.
motors and gear trains available.
But since the cam arrangement differs from that of a re Changing Gear Boxes
gular recorder, the writing speed is based on strikes-per-15
seconds rather than strikes-per-second. Writing speed is about
Open recorder. Remove gear box spring. More gear box
half as fast as that of a recorder without the F1 A.
in direction of arrow on its case. Life out from top. Don't
Strikes/15 sec. 124 8 12 16 20 24 32 force or lift from bottom.
Motor (rpm) % 1 2 4 6 8 10 12 16
Insert new gear box bottom in first. Slide into position
against arrow direction. Replace gear box spring. 11
F217 AMPLIFIER FEATURE: SYMPTOM POSSIBLE CAUSE SERVICE HINT
Input terminals for recorders with the F217 feature are Mem records above or below Meter zero out of adiuftmem Remove front nameplate
zero with no signal applied Adiust mechanical zero
binding posts on the case rear. The slide switch controls both
Mem can't be zeroed Stylus bent , cross arm bent Return instrument to factory
amplifier and motor power. Mem reads zero with-signai Meter open Connect ions to Check meter (Do not use VOM]
applied meter open, multiplier Check wiring to galvo
resistor open Check plug and terminal wiring
Mechanical Zero: wReitahd VOOutM multiplier resistor
With power off and striker bar allowing free swing of Mem hangs above zero Dust in mem pivots Return recorder to factory
Offset stylus visibly bem Meter has been overloaded Return recorder to factory
meter stylus {shut off recorder when striker bar does not
Recorder has continuous Stylus bent, rubs on chart Return to factory
impinge on stylus), adjust mechanical zero located behind trace paper
front nameplate. Mem reads consistently Polarity to meter reversed Check wiring to mating socket
below zero Check polarity of signal being
recorded
Electrical Zero & Calibration: aRt evrioelwi mwoidned owPaper crinkles Ttoe eknmgaog es pdoriovle ngoeta rseated tUankele-tucpn srpeotaoiln iinn gfu crtlihpe r rensoetacth
With power on and input binding posts shorted together, Rther'o01u1g hP raepceorr ddeoresn't drive Pmedrf'oivreatdiornusm n oGt eeanrg targaemd tRaenlosa dB efonldlo twabinsg o nlo agdeainrg t rmamsr ruc
doein t engage drive drum slightly for end play Bend gear
adjust Zero control accessible through case rear for zero trace tram spring for more tension
on chart. Tear-oft Paper doesn t drive Drive belts not seeled on Seat drive betrt as shown in
through tear off Hoi take-up roller Areo riding loading instructions
Remove short. Feed in an accurate signal equal to full- in large center groove of
drive belt roller
scale marking and adjust "Calibrate" control for full-scale Paper taari on drive drum Roll of chart paper is Reload tak mg care chaM
spireled paper is perfectly aligned
trace. This control allows a variation of ±.10% from full-scale
Chart advance thumbwheel Tab that disengages gear Remove gear tram and
design point. it locked tram is bent straighten tab
When testing, refer to Exploded View.
Troubleshooting and Repair Other than service hints outlined on this page, we recom
mend factory service by technicians trained and equipped to
troubleshoot and repair your recorder. Should you wish fac
Your Rustrak recorder is engineered for long and depend
tory repair assistance, pack your recorder in a carton equal
able service. It needs no maintenance schedule or lubrication.
to the original packaging. Insure to full value and ship pre
But as a precision instrument, it should be given the best
paid. Include a letter giving full details with your packing list.
of care.
Many problems during use are due to improper chart Send to:
loading, incorrect wiring or mishandling. Customer Service Department
Typical problems are shown in the accompanying chart. Rustrak Instrument Div., Gulton Industries, Inc.
Municipal Airport, Manchester, N. H. 03103
12
- 3 -
1. INTRODUCTION
In 1973 the U.S. Geological Survey (USGS) decided to build inexpensive horizontal strainmeters
that could be used to study small tectonic stress changes in the earth's crust, caused by slip at depth
along the San Andres Fault. The object of this experiment was to determine if it is possible to observe
changes in the crustal strain field before the occurrence of nearby moderate-to-large earthquakes.
This paper describes in detail, design of the horizontal Invar wire strainmeters at the USGS in
Menlo Park, field installation of these strainmeters in areas near Parkfield, Bear Valley, San Juan
Bautista, and San Francisco, California (Figure 1), and maintenence practices required to allow mean
ingful data to be collected. Problems encountered during the development and installation, along with
our solutions to these problems will be discussed.
1 1 HISTORICAL BACKGROUND
The first strainmeter we investigated used a commercial transducer developed by Diax Corp., in
La Jolla, California (see Appendix 9.3). This instrument was assembled in the U.S. Geological
Survey's Presidio vault in San Francisco, California (Figure 2). This vault was originally an old
ammunition bunker dating back to the Spanish American war. The transducer was bolted to a steel
support resting on the floor and the sensing element was attached to one end of a 10 meter length of
invar wire. The other end of the wire was attached to a second steel support also resting on the floor of
the bunker. The voltage output of the transducer was amplified with a PAR Lock-in Amplifier. This
instrument proved to be noisy (due apparently to mechanical instability of the coupling) and thermally
sensitive, but provided valuable experience on strainmeter and coupling design.
Our next attempt coupled the same transducer, and the anchor end of the invar wire directly into
the sandstone below the tunnel floor. Thermal jostling of the blocks of concrete forming the floor
apparently generated a noisy record. Two existing bore holes, about three meters apart, in one of the