Reftek 151D User manual

REF TEK 151D Broadband
Seismometer Users Guide
151D-UG
Rev A
12/4/2023
This REF TEK manual provides installation and basic operating procedures for the
151D Seismometer and its related products. Guidelines for initial installation with
and without thermal cover are also provided.
Reftek Systems Inc.
75 MacDonald Ave, Unit 1
Dartmouth, NS B3B 1T6
Canada
Phone: [phone]
Email: [e-mail]
www.reftek.com

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Revision History:
Revision
Date
Reason for change
Pages
A
2023.12.04
Initial Release
All
Copyright© 2023 Reftek Systems Inc.
All rights are reserved. No part of this manual may be reproduced,
copied or transmitted in any form outside the approved recipient’s
organization without written permission from Reftek Systems Inc.
Printed in CANADA.

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REF TEK Support and update notifications
As a valued user of REF TEK equipment we would like to provide the
best support possible by keeping you up to date with our product
updates.
If you would like to be notified of any REF TEK product updates please
spend a couple of minutes to register with the REF TEK customer
support team.
To register, email your company information and the REF TEK
products you own to [email protected] or complete the form on our
website at: https://reftek.com/submit-ticket
Any updates or new information required will be shown on our
website’s http://reftek.com/technical-support page.
Support Phone: [phone]
Support Email: [email protected]
Thanks,
Your REF TEK support team
The latest version of REF TEK manuals can be found at
https://manuals.reftek.com

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Contents
1General Description .....................................................................................................................1
1.1 Description .................................................................................................................................................1
1.2 Specifications..............................................................................................................................................2
1.3 Leveling and Orientation Controls..............................................................................................................3
2151D Pre-Installation ...................................................................................................................4
2.1 151 Kit Contents .........................................................................................................................................4
2.2 Checklist for environment ..........................................................................................................................4
2.3 Site Preparation..........................................................................................................................................5
2.4 Unpack........................................................................................................................................................6
3Installation ..................................................................................................................................7
3.1 Move and position the REF TEK 151D ........................................................................................................7
4Level and Power-Up.....................................................................................................................9
4.1 Level............................................................................................................................................................9
5Install the Optional REF TEK Thermal Cover ................................................................................10
6Configuring the DAS and Start Up Procedure ..............................................................................11
6.1 Configure the DAS to control a 151D. ......................................................................................................11
6.2 Connect the 151D to the DAS...................................................................................................................11
6.3 Check Mass Positions. ..............................................................................................................................12
6.4 Mass Position Troubleshooting ................................................................................................................13
6.4.1 User initiated Unlock. ............................................................................................................................13
6.4.2 User initiated Mass Recenter.................................................................................................................13
6.5 Check on Data Output/Sensor Operation.................................................................................................14
7Pin-Out......................................................................................................................................15
8Technical Reference...................................................................................................................16
8.1 Mass Position Centering...........................................................................................................................16
8.2 Calibration ................................................................................................................................................17
8.2.1 Sine Wave Calibration Example .............................................................................................................17
8.2.2 Step pulse Calibration Example .............................................................................................................19
9151D Characteristics ..................................................................................................................22
9.1 151D-120 Transfer Function.....................................................................................................................22
9.2 Characteristic curves ................................................................................................................................23
10 Packing and Transportation........................................................................................................24
10.1 Warranty Statement.................................................................................................................................25
10.2 Warranty/Non-Warranty Service .............................................................................................................25
10.3 Static sensitive device protection.............................................................................................................26

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1General Description
1.1 Description
The 151D is a force-balance feedback broadband seismometer. This
integrated seismometer incorporates 3 independent sensors mounted
symmetrically and combined to provide orthogonal Z-N-E outputs. The
151D incorporates the following functions: control, power-conversion and
feedback. The 151D offers low self-noise, large dynamic range, good
stability and quick installation as well as easy to use features.
The main characteristics of the 151D are as follows:
•Stable force-balance electronic feedback system.
•Frequency range: 120sec~80Hz (See Section 10)
•Self-noise below the NLNM in the range 145 seconds to ~10Hz.
•Automatic and electronic unlocking of the masses.
•Built in functionality for remote centering of the mass position.
•Leveling mechanism includes a bubble level and adjustable feet with
three locknuts.
•Powered by a single +12V DC with low power consumption.
Three separate mechanical sensors are combined together to provide a
vertical (Z; U-D), and two horizontal (X; E-W and Y; N-S) outputs. They are
mounted symmetrically on the circular base. The internal circuit boards are
fixed above the masses. A wire harness and sockets are used to connect the
mechanical and electronic parts.

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1.2 Specifications
No
Item
Specifications
1
Sensor Type
Symmetrical Tri-axial
2
Feedback
Force balance with capacitive displacement transducer
2
Frequency Response
120 sec —80 Hz (Flat to ground velocity)
3
Sensitivity
2000 V/m/s (Differential output)
4
Output Signal
±20 V (Differential output)
5
Dynamic Range
> 150 dB (0.01—0.05Hz)
> 160 dB (1.0—10Hz)
6
Output Impedance
Less than 100Ω
7
Calibration
~ 10 m/s²/A
8
Leveling
Integrated bubble level
Adjustable leveling feet with locknuts (3)
9
Mass Position
3 independent outputs:-10 —+10V (Single-end)
10
Mass Locking
Automatic and remote control
11
Distortion
Total distortion less than -60dB
12
Cross Axis Coupling
Less than 1%
13
Mechanical Zero
No need for adjustment in ± 20° C
14
Power-Fail Protection
Yes
15
Signal Overload
Protection
Yes
16
Auto-recovery time
From Power Fail: ~10 Minutes
From Signal Overload: ~10 Minutes
17
Power Input
9 to 30 VDC
18
Operating
Temperature
-25°C to +60°C
19
Power Consumption
0.65W
20
Water Tight Integrity
IP 67
21
Case
CAE Aluminum, Anodized
22
Dimensions
Diameter 24 cm x Height 24 cm (with feet and connector)
23
Weight
~12.7 kg
24
Connector
FL-570125-26S (Same pin-out as 180-Wrangler)

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1.3 Leveling and Orientation Controls
Setup and adjustment is provided through controls on the outside of the
unit. These controls allow leveling and orientation of the 151D.
FIGURE 1-1 151D TOP VIEW
Orientation: The orientation line is used to orientate the seismometer in the
North and South direction.
Bubble Level: The Bubble Level is used to check the level of the
Seismometer as leveling adjustments are made.
Adjustable Feet: Three Adjustable Feet are provided to level the
seismometer. Use the Locknut to lock each adjustable foot after the
instrument is level.
Connector: The Connector is used to connect the equipment cable to the
seismometer.
Top Orientation Marker
Leveling feet
(x3)
Bubble Level
Connector

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2151D Pre-Installation
The frequency response of the 151D-120 is 0.00833 (120 sec) ~ 80 Hz. The
working environment should meet the requirements for accurate observation
of mid and long period seismic waves.
2.1 151 Kit Contents
Item
Description
Part Number/Comment
1
151D Seismometer w/ shipping
container
151D-120 (R-151D-120)
1
Connection Cable
Optional
1
Datasheet
Envelope
NOTE: Keep all packing material and instructions for shipping the seismometer.
2.2 Checklist for environment
The seismometer needs to be placed in a location protected from the
environment. Use the following checklist to help determine and prepare the
location before installation.
•The mounting surface should be clean (no loose material), close to
level and preferably well connected to the bedrock.
•The seismometer should be sheltered from wind and not exposed to
direct sunlight.
•The location for the seismometer should be thermally stable. A
thermal insulated cover (outside of the seismometer) can be used to
attenuate temperature variation.
•For better results, human activity around the seismometer should be
minimized.
•Magnetic sources should not be placed nearby because it may cause
noise and interfere with the normal observation of the seismometer.
•Place the seismometer in a secure location.

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2.3 Site Preparation
Prepare and clean the mounting surface so that it is free from any loose
materials.
For best results, the installation site should protect the seismometer from
temperature extremes, vibrations from other equipment, and isolated from
air currents.
The 151D seismometer should be installed so that it is aligned and
orientated North to South. To facilitate this, it is recommended that the user
mark a permanent (or semi-permanent) scribe line onto the mounting
surface before installing the 151D. The scribe line should run North ->
South, be about 2 feet long and be located where the North-South line on
the 151D will be installed.
FIGURE 2-1 NORTH ARROW

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2.4 Unpack
The 151D is shipped from REF TEK in a reusable insulated shipping
container with seismometer case.
The 151D comes in the Vertical position with the masses locked.
It is ready for use so adjustment should not be necessary*.
NOTE: *Visually inspect the 151D for damage.
Unpack the 151D from its shipping container by removing the packing foam
located around the 151D.
Gently remove the 151D seismometer from the shipping box.
NOTE: Keep the seismometer upright as much as possible. Never turn the
seismometer on its side or upside down while handling it.

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3Installation
3.1 Move and position the REF TEK 151D
Note: If you have not already done so, scribe a North-South line on the
mounting surface.
Install the North orientation pin in the provided hole of the base.
Figure 3-1 North Pin
1. Install the South orientation pin in the provided hole of the base.
Figure 3-2 South Pin
2. Move the 151D seismometer to the surface where it is to be installed.
3. Orientate the seismometer in the North direction using the North orientation pin as a
guide as shown in Figures 3-2 and the North arrow on the top of the 151D
(See Figure 3-4).
4. Make sure that the 151D is secure. The 3 Adjustable Feet should not shift or rock
relative to the installation surface.

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FIGURE 3-3 NORTH ARROW

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4Level and Power-Up
4.1 Level
1. While checking the Bubble Level, rotate the 3 Adjustable Feet to move the bubble to
the center position.
2. Tighten the 3 Locknut Rings but rotating them counter clockwise into the base while the
bubble level indicates a level position.
Note: Very small changes in levels can greatly affect the mass position of the
seismometer.
3. Verify the leveling does not change when the locknut rings are tightened.
4. Wait at least for 2 hours for the 151D to adjust to the surrounding temperature before
powering up.
Locknut Ring

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5Install the Optional REF TEK Thermal Cover
The optional REF TEK thermal cover (151-9802) can be used to help improve
results at certain installation sites. Examples of sites include sites that are
not well insulated (may experience drafts) or sites that experience larger
swings in temperature. The REF TEK thermal cover can help to insulate the
151D and slow the rate at which its internal temperature changes. This helps
to slow and attenuate the amount of drift in the 151D’s output.
If using the optional REF TEK thermal cover use the following steps for
installation of the REF TEK thermal cover (151-9802) after the 151D has been
placed and leveled.
1. Disconnect the (R-180-C021-XX) cable from the DAS.
2. Disconnect the (R-180-C021-XX) cable from the 151D.
FIGURE 5-1 151D CONNECTOR
3. Locate the connector hole in the thermal cover and line it up so that it is
fits over the 151D connector. Reference Figure 5-1.
4. Align and position the cover’s slots with the orientation pins.
5. Make sure that the 151D is secure. The 3 Adjustable Feet should not shift
relative to the installation surface. Check the orientation and bubble levels to be
ensuring the 151D has not shifted.
6. Connect the 26-pin cable (R-180-C021-XX) to the 151D connector through the
thermal cover
7. Attach the other end of the cable to the DAS and proceed to Section 6.

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6Configuring the DAS and Start Up Procedure
6.1 Configure the DAS to control a 151D.
Before connecting the DAS to the 151D, configure the DAS to accept the
sensor. Plug in the DAS to power and connect to the WebUI (see 180-Wrangler
User Guide). The DAS input range should be configured to accept 40V input
range (under the Parameters>Datastream Menu of the Wrangler) and the
channels of the recorder being used should be selected for recording. Sensor
Control Lines need to be configured to allow the DAS to control the sensor. In
the Wrangler the Sensor Control lines can be configured in the
Parameters>Sensor Type>Sensors Control drop down menu. Remember
to select the 151D Bronco, not the 151B. Older versions of firmware may
require the use of the ”Other” functionality. Remember to press Send to
confirm. If using the Other functionality, select “Other” and then Edit lines. All
functions should active low for 7s to toggle the control functionality, with the
exception of UVW and Cal Enable, which requires a continuous low to toggle.
6.2 Connect the 151D to the DAS
1. Connect the seismometer cable to the 151D.
2. Connect the other end of the seismometer cable to the digitizer (DAS).
Note: Do not connect the 151D with an improper cable. Do not apply voltage
beyond rated values to any inputs.
3. Check the connections.

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FIGURE 6-1 CABLE
This will apply power to the 151D, unlock the masses and start the automatic
mass-centering process. You may be able to hear the centering motors
power-up (one for each component) and center the mass for each component.
This process can take several minutes and up to 20 minutes. During this time,
the 151D is in a short period (1 second) mode. See section 9-1 for more
technical information on the mass centering process.
6.3 Check Mass Positions.
After 20 minutes has passed use the Control>Sensor menu of the Wrangler
to check the 151D Mass Positions. Mass Positions are also available in the
Status Menu.

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The Mass position channels can be used to measure the relation of the
seismometers three masses to their optimal centered position. These
channels are read once per second by default in the Wrangler and through
interpretation, can tell you if the sensor is locked, or close to railing (reaching
the limit of travel). If the mass positions are reading more than 4 Volts after
more than 30 minutes of being powered up double check the sensor is level.
If the sensor is level and the mass position voltage is greater than 4 Volts
start the Mass Position trouble shooting procedure.
The mass position channels data can also be recorded (as a separate
datastream) by selecting the correct options in the
Paramters>Datastream>Stream 9 sub-menu screen. The auxiliary data
is recorded as datastream 9 in 16-bit format. See the 180-Wrangler Users
Guide for more information.
6.4 Mass Position Troubleshooting
After powerup, wait at least 20 minutes for the sensor to settle.
6.4.1 User initiated Unlock.
If all three mass positions are reading 12V, and the sensor is level typically
the locking mechanism is engaged. The locking mechanism pushes the
mass against one of the mechanical limits of the sensor, to prevent damage.
Issuing a manual “Unlock”command from the Control>Sensor menu will
initiate the unlock procedure. The mass position should change within 1
minute, and an automated mass recenter will begin.
6.4.2 User initiated Mass Recenter.
If the masses are reading Less than 12 V, but more then 4V, the masses
will need another mass recenter. Individual channels can be “railed” and
read 12V as well, this also typically requires a mass recenter. Issue a
manual Mass Recenter from the Control>Sensor menu for the Channels
the 151D is connected to. Click Mass Recenter. The WebUI of the Wrangler
should confirm the command is sent. The recentering procedure can take
20 minutes. Ideally the mass positions should be <1 V in magnitude after
recentering. The mass position values update every second.

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6.5 Check on Data Output/Sensor Operation
The Monitor page of the Wrangler WebUI can be used to check the 151D
operation.
1. Click on the Monitor button and select the stream activated to record the 151D.
2. Wait for the data image to display .
Note: The display shows the Midpoint of the data and the peak-to-peak
Range of the data in counts

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7Pin-Out
The 151D connector is the FL-570125-26S. The standard 151D cable is the
R-180-C021-XX which is meant to connect the 151D to a 180-Wrangler. The
pin assignment of the 151D output connector is pin-for-pin compatible with
the 180-Wrangler channel connector:
Pin
Signal
A
Vertical positive signal output (+)
B
Vertical negative signal output (-)
C
N-S positive signal output (+)
D
N-S negative signal output (-)
E
E-W positive signal output (+)
F
E-W negative signal output (-)
G
Analog Signal Ground
H
Power Supply (+12V) input
J
Power Ground
K
Calibration Signal input
L
Calibration Enable (Active Low) input
M
Center pin (Active Low) input
N
Lock (Active-Low) input
P
Unlock (Active-Low) input
R
No connection (RS232 Rx)
S
UVW enable (Active-low) input
T
No connection
U
No connection
V
Sensor ID bidirectional (RS232 Tx)
W
Analog ground
X
U Mass position output
Y
V Mass position output
Z
W Mass position output
a
No connection
b
No connection
c
No connection
FIGURE 7-1 CONNECTOR PIN OUT

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8Technical Reference
8.1 Mass Position Centering
A microprocessor circuit inside the 151D provides the function of auto-
adjusting the mass position. An auto-adjusting cycle is initiated by powering
up the seismometer or sending a remote command from the digitizer. Three
motors work in sequence for centering the respective mass. During auto-
adjusting, the seismometer’s period will be switched to 1 second to improve
stability and to reduce centering time. After the auto-adjusting cycle ends, the
period will return to 120 seconds automatically.
For details about auto-adjusting see the flow chart below (Figure 9-1). An
auto-adjusting cycle lasts several minutes (usually less than 20 minutes) and
depends on the current mass position. The auto-adjust cycle has a 20-minute
timeout. If the timeout is reached and the centering process is not completed
the 151D will stop the process and the seismometer will be switched back to
its long period mode, even if all the components have not been centered. In
this case, the user may need to initiate another centering process (See Section
6.2.2 for user-initiated centering).
WARNING: Before auto-adjusting, make sure that the 151D is level and all
masses have been correctly unlocked and no calibration is running.
Note: The 151D mass position outputs have a nominal full-scale range of
±10 Volts.
FIGURE 8-1 MASS CENTERING FLOW CHART