Milltronics MD-2000A, MD-2000A SS Instruction Manual

MD-2000A SPEED SENSOR

Instruction Manual June 2002

Safety Guidelines

Warning notices must be observed to ensure personal safety as well as that of others, and to protect the product and the connected equipment.
These warning notices are accompanied by a clarification of the level of caution 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: This product can only function properly and safely if it is correctly transported, stored, installed, set up, operated, and maintained.

Note: Always use product in accordance with specifications.

Copyright Siemens Milltronics Process

Disclaimer of Liability

Instruments Inc. 2002. All Rights Reserved

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MILLTRONICS®is a registered trademark 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 contents of
this manual are regularly reviewed and
corrections are included in subsequent editions.
We welcome all suggestions for improvement.

Technical data subject to change.

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Siemens Milltronics Process Instruments Inc.
1954 Technology Drive, P.O. Box 4225
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SPECIFICATIONS

Power: » +15 V dc, 150 mA from integrator

Temperature: » -20 to 55° C (-4 to 130° F)

Input: » bi-directional shaft rotation

» 0.3 to 75 rpm operating input

Output: » open collector sinking output, max. 25 mA at 5 V dc

» 2048 pulses / revolution
» 10 to 2,560 Hz operating output

Enclosure: » general purpose

» material : - standard : aluminum

- optional : 304 stainless steel

Cable: » Belden 8770, 3 wire shielded, 18 AWG or equivalent

» max run 305 m (1000 ft)

REFERENCE

Associated Milltronics integrator:
CompuScale III

BW100
BW500

GENERAL

The MD-2000A speed sensor is used to monitor the speed of a weighfeeder or low speed belt conveyor ( see
input specification ). The sensor, coupled to a 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 an encoder which produces two square wave quadrature (90° electrically out of phase) outputs which
are fed to the speed sensor board to determine direction of rotation as well as the speed of rotation.
Power is provided by the integrating device. The 15 V dc supply is regulated to 5 V dc for use by the encoder
circuit and output drive transistors of the speed sensor board.

As the shaft rotates, the two quadrature square waves from the 2048 pulse per revolution encoder are
converted into clockwise (CW) and counter clockwise (CCW) square wave output signals by the intermediate
counter logic. When the shaft rotates in the CW direction, the logic produces pulses at the CW output and the
CCW output is disabled. When the shaft rotates in the CCW direction, the logic produces pulses at the CCW
output and the CW output is disabled.

The logic diagrams detail the operation of the electronics for both clockwise and counter clockwise output
generation. The speed sensor is immune to external vibration that would cause the encoder to oscillate 1/8 of
a revolution or less.

PL-361 1

MOUNTING

The MD-2000A speed sensor is usually coupled to the tail pulley shaft of a weighfeeder. On low speed
conveyers, the speed sensor may be coupled to the tail, bend or snub pulley. The mounting arrangement
requires the input shaft and bearing assembly to bear the weight of the speed sensor. The unit’s arresting
bracket stops the speed sensor from rotating with the shaft.

When mounting the speed sensor, ensure that the shaft alignment is true to avoid stresses on the shaft
bearing. Refer to ( MD - 2000A Series Pulley Mounting ).

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.

SPEED SENSOR INTERCONNECTION

MD-2000A BW100 BW500 COMPUSCALE III

DESCRIPTION TERMINAL TO 1TB

+15 V DC(Red) 1 8 19 30

speed out-CW

(White)

speed out-CCW

(Blue)

Common

(Black)

Ground 5 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 ( MD - 2000A Series Pulley Mounting ).

‘ N/C ’ denotes ‘ no connection ’

2 (7) (16) (31)

3 (7) (16) (31)

4 6 17 32

PL-361 2

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 bearings life is
dependent upon the mounting, the severity of the application and surrounding environment.

SPARE PARTS

Bearing Assembly: - MD 2000A

- MD 2000A SS

Speed Sensor Card - without encoder

- with encoder

PL-361 3