Thermo Scientific 61-12N-64P Service manual

Thermo Fisher Scientific™
Speed Sensor
Model 61-12N-64P
Operating and Service Manual
REC 4374 Rev C
Part Number 136294—English

Ramsey Model 61-12N Speed Sensor REC 4374B Page 2
REC 4374 Rev C
Part Number 136294—English
This document is confidential and is the property of Thermo Fisher Scientific. It may not be copied or
reproduced in any way without the express written consent of Thermo Fisher Scientific. This document also is
an unpublished work of Thermo Fisher Scientific. Thermo Fisher Scientific intends to, and is maintaining the
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Fisher Scientific.
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States and/or other countries.
All other trademarks are the property of Thermo Fisher Scientific and its subsidiaries.
© 2016 Thermo Fisher Scientific, Inc. All rights reserved.

Ramsey Model 61-12N Speed Sensor REC 4374B Page 3
Revision Number
Date Revised
ECO Number
Revision Specifics
Revision A
January 2014
3391
New Release
Revision B
September 22, 2016
4227
Update to Hazardous
Revision C
September 20,2019
5053
Added metric coupling
NO CHANGES TO THIS DOCUMENT WITHOUT AGENCY APPROVAL

Ramsey Model 61-12N Speed Sensor REC 4374B Page 4
Table of Contents
Table of Contents ...............................................................................................4
Introduction .......................................................................................................5
Overview........................................................................................................ 5
Application..................................................................................................... 5
Unpacking and Inspection.............................................................................. 6
Storage .......................................................................................................... 6
Specifications................................................................................................. 6
Installation .........................................................................................................6
Overview........................................................................................................ 6
Coupling Installation ...................................................................................... 7
Restraint Arm Installation .............................................................................. 8
Alternate Sensor Location.............................................................................. 9
Operations........................................................................................................ 12
Maintenance ....................................................................................................12
Service, Repair & Replacement Parts ................................................................ 14
Service and Repair Information.................................................................... 14
Parts Ordering Information.......................................................................... 14
Parts Lists..................................................................................................... 15
Centering Template for Speed Sensor...............................................................16
Contacting Thermo Fisher Scientific ..................................................................17
Appendix A –Drawings..................................................................................... 18

Ramsey Model 61-12N Speed Sensor REC 4374B Page 5
Introduction
This section itodues the Theo Sietifi™ Rase™ Model 61-12N Speed Sensor. It gives an overview of
the deie’s apailities, provides information on installing, operating and maintaining along with technical
specifications and reference drawings.
Overview
The Thermo Scientific Model 61-12N-64P Speed Sensor is designed and constructed for direct connection to a
conveyor tail pulley, snugging roll, or large diameter return roller.
The speed sensor employs an optical pulse generator producing a stream of pulses, each pulse representing a
unit of belt travel. Frequency of the pulse stream is proportional to true belt speed.
Figure 1. Model 61-12N-64P Speed Sensor
Application
The speed sensor is coupled to a rotating shaft which drives a pulse generator inside the housing. The 61-12N-
64P can be used for speeds from 0 to 350 RPM. The frequency of the speed sensor output signal is exactly
proportional to shaft speed and provides the required speed input to a Thermo Scientific Integrator/Totalizer.
CAUTION: The speed sensor has a coupling that is connected to a rotating shaft. Always use
caution and appropriate safeguards around moving equipment.

Ramsey Model 61-12N Speed Sensor REC 4374B Page 6
Unpacking and Inspection
The Model 61-12N-64P Speed Sensor has been properly packaged and inspected prior to shipment. Before
unpacking, be certain to check the package for external damage, as the carrier may often times be held
responsible for shipping damage.
Storage
The Model 61-12N-64P Speed Sensor can be safely stored indoors, between -50 and +85 degrees C (-58 to
+185 degrees F). The unit must be protected against moisture.
Specifications
Supply Voltage: 18-28 VDC
Application: Indoor/Outdoor use
Environment Rating: Type 4X, IP66
Supply Current: 30 mA max.
Output Current: 100 mA max. sinking current
Operating: -40°C to +80°C (-40º to +176ºF)
Temperature: T4 temperature identification
Speed: 350 RPM maximum
Pulse Output Rate: 64 pulses per shaft revolution
Cable Length: 20 AWG (Belden #8772 or equal), up to 500 feet (150 meters)
18 AWG (Belden #1036A or equal), 500 to 3000 feet (150 to 915 meters)
Entity Parameters for Class I, Div. 1: Ui = 28 volts, Ii =93 mA, Pi =660 mW
Humidity: 80% maximum relative humidity for temperatures up to 31°C
decreasing linearly to 50% relative humidity at 40°C.
Pollution Degree: 2
Overvoltage Category: I
Altitude: Up to 2000m
Installation
Overview
The Model 61-12N-64P Speed Sensor must be attached to a pulley shaft which turns at true conveyor belt
speed. Normally, the tail pulley shaft or a snubbing roll shaft satisfies this requirement. In installations where
the tail pulley or snubbing roll shaft is not accessible, an additional pulley must be installed specifically for the
speed sensor.

Ramsey Model 61-12N Speed Sensor REC 4374B Page 7
Coupling Installation
Two methods of coupling the speed sensor to the pulley shaft are shown in Figure 2 and Figure 3. Other
methods may work as well. The most important requirement is that the speed sensor remains free floating and
not rigidly coupled to the conveyor frame.
Note: Never mount speed sensor on a driven pulley.
Use the following procedures for coupling installation:
Method A:
Locate the exact center of tail pulley or snubbing roll shaft. The Centering Template for Speed Sensor located
at the end of this manual may be cut out and used as a centering guide. (Refer to Figure 2.)
1. Locate circle guide over tail pulley shaft and punch center. Drill a 1-/ deep hole usig a / dill.
(Drilling a smaller pilot hole is helpful in assuring correct centering.)
2. Tap this hole usig a /-11 tap.
3. Clean out oil and chips with an appropriate solvent and apply a thread lock retaining compound, such
as LOCKTITE thead loke .
4. Thread in supplied stub shaft coupling (part #037711) so that coupling collar bottoms out against tail
pulley or snubbing shaft. See Figure 2.
5. Insert 61-12N-64P speed sensor into coupling. Be sure to align shaft flat spots with set screws on
coupling. Tighten all set screws securely.
Figure 2. Method A Installation
OR
M12 X 1.75 mm
IMPERIAL
/
131185
METRIC

Ramsey Model 61-12N Speed Sensor REC 4374B Page 8
Method B:
If ustoe’s tail pulle shaft has a / diaete stu shaft etedig fo it ad is oeti ith the
centerline of the driving shaft, use part #002931 to couple 60-12 speed sensor to tail pulley shaft (refer to
Figure 3). This coupling is not supplied with the speed sensor but may be purchased separately from Thermo
Fisher Scientific.
It would be advisable to provide two flat surfaces, 90º apart, on the stub shaft for a good set screw holding
power.
Note: If possible, weld coupling to tail pulley shaft. Do not weld to any part of 61-12N-64P speed sensor.
Align shaft flat spots with set screws on coupling. See Figure 3. Tighten all set screws securely.
Figure 3. Method B Installation
Restraint Arm Installation
1. Attach restraint arm to speed sensor with two (supplied) 5/1  -/ olts. See Figue . The
restraint arm should be mounted in a direction that will allow the sensor restraint arm to twist against
the mechanical stop and in the direction of belt travel.
2. Weld or otherwise secure an appropriate mechanical stop such as a piece of scrap iron (or a bolt) to
the conveyor frame. Rotate restraint arm to let it rest on the stop. See Figure 4. Make the mechanical
stop large enough to accommodate some lateral movement of the restraint arm.
3. Fit one end of the supplied restraining spring through the hole in the end of the restraint arm. Attach
the other end to the conveyor frame. Location should be such as to give a 1/2 inch spring stretch. Do
not over-tighten spring as this may cause premature failure. See Figure 4.
4. Although not required, it is recommended that a rock or step shield be fabricated and installed around
the speed sensor.
5. Do not connect power to the machine or turn on the unit until you have read and understood this
entire chapter. The precautions and procedures presented in this chapter must be followed carefully
to prevent equipment damage and protect the operator from possible injury.

Ramsey Model 61-12N Speed Sensor REC 4374B Page 9
Note: The pupose of this outig aageet is to allo the speed seso to float ad aoodate
any slight misalignment of the coupling. Therefore, no resultant bearing stress is applied due to misalignment,
o ill a slight ole of the deie esult i eletial eos.
Alternate Sensor Location
On installations where the tail pulley or snubbing roll shaft is not accessible and additional pulley must be
installed specifically for the speed sensor. When using an additional pulley for the speed sensor, the following
requirements are essential:
1. Select the proper pulley diameter to provide a shaft RPM within the range of the speed sensor (at
rated belt speed or over the range of belt speeds that are of concern).
2. Locate the pulley on the clean side of the return belt to minimize material build up on the pulley.
3. Install the unit in such a manner as to provide 15 to 30 degrees contact wrap on the pulley. Any
slippage between belt and pulley will decrease the belt scale accuracy.
CAUTION. Unless the installation is consistent with the illustrations shown in Figure 2, Figure 3,
Figure 4, and as described above, the warranty on the device is void.
Figure 4. Mounting Illustration

Ramsey Model 61-12N Speed Sensor REC 4374B Page 10
1. Speed Sensor must not be mounted rigid. Use restraint arm and retaining spring. Mechanical stop and
spring mount are by others.
2. Attah spig i loatio suh as to gie / spig steth.
3. All wiring by others in accordance with system field wiring diagram and applicable codes.
Figure 5. Outline and Mounting Dimensions
Notes:
1. Speed Sensor to be driven by conveyor tail pulley shaft or by special return roll.
2. Unit must be directly coupled to driving shaft. Do not drive with chains, belts, gears, etc.
3. Custoe to poide tapped hole . deep.
4. Do not rigid mount speed sensor.

Ramsey Model 61-12N Speed Sensor REC 4374B Page 11
Electrical Wiring
Use the following procedures to make electrical connections:
1. Remove the terminal strip cover (Figure 1) and the dust plug from the threaded conduit aperture in
the speed sensor housing.
2. Install 1/2 inch flexible conduit to the speed sensor housing.
3. For 61-12N-64P use Belden 8772 or equivalent, 3 conductor, 20 AWG, shielded. Maximum distance is
500 feet (150 meters). For distances of 500 to 3000 feet (150-915 meters), use Belden #1036A or
equivalent, 3 conductor, 18 AWG shielded. Cable temperature rating must exceed minimum and
maximum ambient conditions.
4. Do not put speed sensor cables in the same conduit as power wiring.
5. Connect one wire to each of terminals 15, 16, and 17 as shown in Figure 6. Replace the terminal strip
cover.
CAUTION: The three wires connecting the speed sensor to the integrator/totalizer must be shielded.
Refer to system wiring diagram for proper shield termination.
6. Do not terminate cable shield at speed sensor. Follow system field wiring diagrams for termination at
control instrument only.
Refer to drawing 07392BE041 at the end of this manual for Class I hazardous location installations.
Refer to drawing 07392BE042 at the end of this manual for Class II or III hazardous location
installations.
Refer to drawing 07392BE043 at the end of this manual for non-hazardous area location
installations.
Figure 6. Field Wiring
SPEED SENSOR
61-12N-64P

Ramsey Model 61-12N Speed Sensor REC 4374B Page 12
Operations
Overview
The speed sensor element employs an optical, pulse generator which produces a stream of pulses, each pulse
representing a unit of belt travel. The frequency of the pulse stream is proportional to true belt speed. The
pulse output signal is fed to the Integrator/Totalizer.
Figure 7. 61-12N-64P Output Voltage Waveform
Model 61-12N-64P
The 61-12N-64P has a 64 pulse per revolution optical encoder and can be used for speeds from 0 to 350 RPM.
The output of the 61-12N-P is a ope-dai tpe, hih euies a eteal pull-up resistance. Nearly all
Thermo Scientific Belt Scale Integrators provide this pull-up resistance internally.
Maintenance
Overview
When performing scale calibration, it is a good practice to inspect the shaft coupling for tightness. Inspect the
shaft seal yearly for damage and cracks. If the shaft seal is defective, replace the speed sensor. Also verify that
the restraint arm is free to move. If arm has worn a slot in the restraint stop and the restraint bar cannot float
back and forth as well as against the spring, corrections should be made.
Calibration
No adjustment or calibration of the device is necessary.
4 to 20 VDC,
depending on host
instrument

Ramsey Model 61-12N Speed Sensor REC 4374B Page 13
Troubleshooting
1. Place a DC voltmeter across field terminals 17 (+) and 16 (-) of 61-12N-64P speed sensor.
2. Reading should be equal to the source voltage from the integrator.
3. If no voltage present, check at integrator terminals (see scale integrator manual).
4. If voltage is present, check field wiring. If no voltage present, repair or replace integrator.
5. Place AC voltmeter across field terminals 15 and 16 of 61-12N-64P speed sensor.
6. With conveyor stopped, output should be 0.0 VAC.
7. Start conveyor belt; output should be greater than 4 VAC.
8. If no voltage is present, check the sensor with the wire from terminal 15 disconnected.
9. If no voltage is present while running, repair or replace the speed sensor.
10. If greater than 4 VAC is present, check field wiring.

Ramsey Model 61-12N Speed Sensor REC 4374B Page 15
Parts Lists
The list below provides part numbers and descriptions of the replaceable parts for the 61-12N-64P Speed
Sensor.
ITEM DESCRIPTION PART NO.
61-12N-64P (64 pulse, 24 VDC) 133748
Clamp Bar (Restraint Arm) 002920
Coupling, Stub Shaft, Speed Sensor 037711 (IMPERIAL) / 131185 (METRIC)
Coupling Shaft, .625 Bore 002931
Spring, Extension for Clamp Bar 001988
Cover, Junction Box 004156

Ramsey Model 61-12N Speed Sensor REC 4374B Page 16
Centering Template for Speed Sensor

Appendix A –Drawings
List of drawings
Drawing 07392BE041
Drawing 07392BE042
Drawing 07392BE043

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