Milltronics MD-36 Instruction Manual

MD-36 SPEED SENSOR

Instruction Manual PL-392 January 2001

Instruction Manual PL-342 August 2001

33453420
Rev. 3.4

Safety Guidelines

Warning notices must be observed to ensure personal safety as well as that of others, and to protect the pr oduct and the connected equipment.
These warning notices are accompanied by a clarification of the level of caut ion to be observed.

Qualified Personnel

This device/system may only be set up and operated in conjunction with this manual. Qualified personnel are only authorized to install and
operate this equipment in accordance with established safety practices and standards.

Warning

Note

This product can only function proper ly and safely if it is correctly transported, stored, installed, set up , operated, and maintained.

:

Always use product in accordance with specifications.

:

Copyright Siemens Milltronics Process

Disclaimer of Liability

Instruments Inc. 2000. All Rights Reserved

This document is available in bound version and in
electronic version. We encourage users to purchase
authorized bound manuals, or to view electronic versions as
designed and authored by Siemens Milltronics Process
Instruments Inc. Siemens Milltronics Process Instruments
Inc. will not be responsible for the contents of partial or
whole reproductions of either bound or electronic versions.

MILLTRONICS®is a registered t r ad emark of Siemens Milltronics Process Instruments Inc.

While we have verified the contents of this
manual for agreement with the instrumentation
described, variations remain possible. Thus we
cannot guarantee full agreement. The content s of
this manual are regularly reviewed and
corrections are included in subsequent editions.
We welcome all suggestions for impr ovement .

Technical data subject to change.

Contact SMPI Technical Publications at the following address:

Technical Publications
Siemens Milltronics Process Instruments Inc.
1954 Technology Drive, P.O. Box 4225
Peterborough, Ontario, Ca nad a, K9J 7B1
Email: techpubs@milltronics.c om

For the library of SMPI instruction ma nuals, visit our Web site:

© Siemens Milltronics Process Instruments Inc. 2001

www.milltronics.com

SPECIFICATIONS

Power: - +15 V dc, 25 mA from integrator
Temperature: - -40 to 55° C (-40 to 130°F)
Input: - shaft rotation 0 to 1,000 rpm, bidirectional
Output: - open collector sinking output, max. 25 mA at 15 V dc

- 36 pulses / revolution

- 0 to 1,000 rpm = 0 to 600 Hz
Input:output: - 1:1 (speed ratio)
Enclosure: - MD-36 : aluminum

rating: Type 4/NEMA 4/IP 65

- MD-36A : aluminum

- MD-36SS : 304 stainless steel
Approval: - MD-36 - CSA & FM : class II, GR. E, F&G, class III
Cable (optional): - Belden 8770, 3 wire shielded, 18 AWG or equivalent

- max run 305 m (1000 ft)

REFERENCE

Associated equipment: Milltronics integrator

Compuscale
Compuscale II
Compuscale IIA
Compu-M
Compuscale III
Accumass BW 100
Accumass BW 500

GENERAL

The MD-series speed sensor is used to monitor the speed of a belt conveyor. The sensor, coupled to the
motor or pulley shaft, converts the rotation of its input shaft into an encoded speed signal. The speed
signal is transmitted to the integrating electronics for use in computing the rate of material flow.

CIRCUIT OPERATION

The speed sensor is made up of a main shaft rotating in a bearing assembly fixed to the enclosure. The
shaft turns a toothed disk, which is divided into 36 teeth each separated by a gap equal to the tooth width.
The encoder card is mounted such that the two optocouplers straddle the disk’s teeth.

( Refer to FIG. 5 )

Power from the integrating de vice i s used to energize the two optocoupler LED’s and to feed the 5V dc
regulator. The 5V dc bus powers the logic circuitry and the output driver transistors.

As the shaft is rotating, the 36 toothed wheel modulates the light crossing within each optocoupler (O C1
and OC2). The resulting outputs are two 50% duty cycle square waves that are phase shifted by 90
degrees electrical or 1/4 cycle (one cycle of 360 degrees electrical corresponds to the width of one tooth
and one gap). This configuration provides directional discrimination.

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95/01/03

The optocouplers’ square wave outputs are converted into CW and CCW square wave output signals by
the intermediate logic. When the shaft rotates in a CW direction, the logic produces pulses at the CW
output (1RC 2) and the CCW output is disabled. When the shaft rotates in a CCW direction, the logic
produces pulses at the CCW output (1RC 4) and the CW output is disabled.

The logic diagrams detail the operation of the electronics for both the clockwise and counterclockwise
output generation.

The speed sensor is immune to external vibration that would cause the toothed wheel to oscillate 1/4
cycle (1/2 tooth width or 5° of shaft rota tion) or less.

MOUNTING

The MD-36 speed sensor c an be coupled to a tail pulley, bend pulley or motor shaft. In the general
(floating) mounting arrangement, the input shaft and bearing assembly bear the weight of the speed
sensor. The unit’s arresting bracket stops the speed senso r from rotating with the shaft.

When mounting the speed sensor, ensure that the shaft alignment is true to avoid stresses on the
shaft bearing.

Mounting Reference Drawings:

MD-36 Pulley Mounting Figure 2
MD-36 Motor Shaft Mounting Figure 3

For preferred mounting locations, refer to the as sociated belt scale or weigh feeder instruction manual.

INTERCONNECTION

ALL WIRING MUST BE DONE IN CONJUNCTION WITH APPROVED

CONDUIT, BOXES AND FITTINGS AND TO PROCEDURES

IN ACCORDANCE WITH ALL GOVERNING REGULATIONS.

Interconnection between the speed sensor and the integrator should be made with 3 wire shielded, 18
AWG cable (Belden 8770 or equivalent).

Ground the shield at the integrator ONLY!

FLEXIBLE CONDUIT IS RECOMMENDED SO EXCESS STRESS

IS NOT APPLIED TO THE SHAFT BEARINGS.

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SPEED SENSOR INTERCONNECTION

MD-36 C

Description Terminal

ompuscale Compu II Compu IIA C om pu - M Compu III

to 1 TB to 1 TB to 1 TB to TB1 to TB1 to TB1 to TB1

ccumass

A

BW 100

Accumass

BW 500

+ 15 V dc 1 1 15 12 11 30 8 19

speed

2 (2) (16) (13) (12) (31) (7) (16)

out-CW

speed

3 (2) (16) (13) (12) (31) (7) (16)

out-CCW
Common 4 4 17 14 13 32 6 17

Ground G N/C N/C N/C N/C N/C N/C N/C

Terminal positions in brackets denote that only one signal may be connected at one time. To determine
direction of rotation refer to Figure 3

‘ N/C ’ denotes ‘ no connection ’

MAINTENANCE

The speed sensor electronics normally requires no maintenance, however a program of periodic checks
would be beneficial. The enclosure and circuit board should be cleaned if necessary, but only when the
power is disconnected using a vacuum cleaner and a clean dry paint brush. Check all electrical contacts
for corrosion and arcing.

The speed sensor bearing should be periodically checked for corrosion, wear and seizing. The bearing‘s
life is dependent upon the mounting, the severity of the application and surrounding environment.

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95/07/05