Siemens OCM III 7ML19985AB01 User Manual
Instruction Manual November 2005
open channel
OCM III
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.
Unit Repair and Excluded Liability:
• The user is responsible for all changes and repairs made to the device by the user or the user’s
agent.
• All new components are to be provided by Siemens Milltronics Process Instruments Inc.
• Restrict repair to faulty components only.
• Do not reuse faulty components.
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. 2005. All Rights Reserved
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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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TABLE OF CONTENTS
TITLE PAGE
ABOUT THIS ...
About This Ma nual 7
About the OC M-3 7
SPECIFICATIONS 9
Programmer 10
Transducer 11
Temperature Sensor 11
Cabling 11
Communication Softwa re 11
INSTALLATI ON
Installing the OCM-3 13
Outline and Mounting 13
OCM- 3 Layout 14
System Diagram 15
Installing the Transducer 16
Installing the Temperature Sensor 16
mA Output 17
Relays 17
Synchronization 18
Power Conne ctions 19
Installing the Memory Back-up Ba ttery 20
Communicating Via Compute r 20
Installing the Programmer 20
7ML19985AB01 OCM III 3
START UP
General 21
Keypad 21
Legend 22
Initial Start Up 22
Fundamenta l Checks 25
OPERATION
Memory 27
Security 27
Units 27
Flow Calculation 28
Display 28
Damping 29
Relays 30
mA Output 30
Fail-Safe 31
Flow rate a nd Totaliz ing 31
Logging 3 2
Blanking 34
Temperature 34
Time and Date 34
Emulation Mode 35
Reset 35
Flow Velocity I nput 36
Auxiliary Head Input 36
DC Output 37
Diagnostic Aids 37
7ML19985AB01 OCM III 4
‘D’ PARAMETER LISTING 39
‘F’ P ARAME TER LIST ING 41
‘P’ PARAMETER LISTING 43
‘U’ PARAMETERS FOR P3 PRIMARY ELEMENT 51
Simple Exponential Device s, P3 = 0 53
BS-3680 Rectangular Flume, P3 = 1 58
BS-3680 Round Nose Horizonta l Crest Weir, P3 = 2 60
BS-3680 Trapezoidal Flume, P3 = 3 62
BS-3680 U - Flume, P3 = 4 64
BS-3680 Finite Crest Weir, P3 = 5 66
BS-3680 Thin Plate Rectangular Weir, P 3 = 6 68
BS-3680 Thin Plate V-Notch Weir, P3 = 7 70
Rectangula r Weir (Contra cted), P3 = 8 72
Round Pipe, P3 = 9 74
Palmer-Bowlus Flume, P3 = 10 76
H - Flume, P3 = 11 78
Universal Head vs. Flow, P3 =12 80
Rectangula r Area x Velocity, P3 = 13 82
Trapezoidal Area x Velocity, P3 =14 84
Modified Trapezoidal Area x Velocity, P3 = 15 86
U Channel Area x Velocity, P3 = 16 88
Circular Area x Velocity, P3 = 17 90
Gull-Wing Area x Velocity, P3 = 18 92
Egg-Shaped Area x Velocity, P3 =19 94
Universal Area x Velocity, P3 = 20 96
APPENDICES
Maintenance 99
Error Codes 100
Communications 101
7ML19985AB01 OCM III 5
7ML19985AB01 OCM III 6
ABOUT THIS ...
ABOUT THIS MANUAL
Although the OCM-3 is very ‘approacha ble’ due its dialogue capa bilities and intuitive
operation, the user should be familiar with this manua l. This manual provide s the user
with the ne cessary information require d to install, sta rt up and operate the OCM-3.
As the OCM -3 prompts the user with spe cific message s in a step-by-ste p fashion
during programming, the Start Up section serves essentially to complime nt the
OCM- 3. Start Up provides the use r with instructions on the use of the programme r
and a n overview of the programming requirements.
The ‘D’, ‘F’, ‘P’ and ‘U’ para meters listed in the Paramete rs section provide a quick
refe rence of the available programming and display parame ters and the ir options. The
‘U’ parameter listing also provides mathema tical and graphical details as a reference
to assist the user in programming the OCM-3 to the primary element being used. The
user is urge d to rely on the ma nufacturer’s specification for obta ining and identifying
the primary element to which the OCM-3 is being applied.
In short,
If you want to know about
the product About This . . .
getting started Installa tion
how it works Opera tion
Read
Spe cifications
Start Up
Parame ters
Appendices
ABOUT THE OCM-3
The OCM-3 is to be used only in the manner
outlined in this instruction manual.
The Milltronics OCM-3 , Open Channel Meter, is an electronic instrument designed to
measure flow in open channels. I t is housed in a polycarbonate e nclosure and comes
with a removable programmer. As a system, it is used in conjunction with a re mote
ultrasonic transducer (or auxiliary head measurement device) and a temperature
sensor.
The OCM-3 transmits a pulse signal to the transducer which is then emitted as
ultrasonic pulses. The pulses echo off the water surface and are then sensed by the
transducer. The time for a pulse to echo back from the water surface is temperature
compensated and converted into a measurement of head.
7ML19985AB01 OCM III 7
The OCM-3 converts the head measurement into flow rate, but also provides a
velocity sensor input for applications whe re a flow ve locity measurement is re quired to
perform the flow calculation. The flow rate is totalized and stored in a comprehensive
data log to provide deta iled flow analysis.
Programming of the OCM- 3 allows the opera tor to se lect the flow ca lculation specific
to the prima ry measuring device ( flume, we ir or pipe). Spe cial e mphasis has be en
placed on providing the most accurate flow calculations possible. To this end, specific
routines have been writte n to comply with the British Standards Institute’s
Specifications BS-3680. These routines calculate correction factors taking into
account se cond order effe cts such as approa ch velocity and bounda ry layer. In the
event that flow measurement is not covered by one of the flow calculations provided,
the O CM-3 ca n be programme d for flow measure ment using one of the universal
flow calculations.
The OCM-3 provides serial communication for re mote programming, data log re trieval
and print out for devices such as computers, PLC s and printers. Milltronics provides a
standa rd utilities softwa re package for OCM -3 programming, re mote display and data
retrieval. Howeve r, the use r is not limited to the software provided. T he user ca n
develop his own softwa re program to pe rform ta sks suited to his specific nee ds.
The OCM-3 features:
✓ multi field illuminated LC D, for ‘Flow and Tota l’ and ‘Relay Status’ display
✓ 0 or 4 to 20 mA output
✓ three multipurpose rela ys, including remote totaliza tion
✓ 1 to 2 4 months data log, subject to logging ra te
✓ extensive se rial communication, including RS-2 32
✓ removable infra-red programme r
✓ AC and D C (bi-current) opera tion.
7ML19985AB01 OCM III 8
SPECIFICATIONS
Power: » dc supply: » 9 to 30 V D C, 8 W max
» ac supply: » 100/115/200/230 V ac ± 15%, 50/60 Hz,
20 VA max
Environmental: » location » indoor /outdoor
» altitude: » 2000 m max
» ambient temperature » – 20 to 50 °C (–5 to 122 °F)
» relative humidity » suitable for outdoor (Type 4X/Nema 4X
» installation category » II
» pollution degree » 4
Memory
back-up: » 3 V lithium battery (NEDA 5003LC or equivalent)
» operating life 1 year
» ‘SuperC ap’ capacitor for back-up
during battery replace ment
Range: » 0.3 m min to 1.2 m max ( 1 to 4 ft)
0.6 m min to 3 m max (2 to 10 ft)
Resolution: » 0.2 mm (0.007")
and / or
IP65 enclosure)
Accuracy: » ±1 mm/m, calculated error less than 0.02%
Temperature
Compensation: » external sensor to compensate over
Programming: » via supplied progra mmer and
Inputs: » velocity sensor and
Outputs: » transducer drive: » 44 Khz, 400 Vpp pulses of 0.1 msec typical
7ML19985AB01 OCM III 9
the ope rating range
communication link
auxiliary head » range: » 0 to 10 V dc
» resolution: » 2.7 mV
duration at a 100 msec typical repetition rate.
» instrumentation: » range: 0-20 or 4-20 mA
» resolution: 5 uA
» maximum loading: 1 KΩ
» isolation: 300 V ac continuous
» relays: » 3 alarm/control relays
» 1 form ’C’ SPDT contact per relay, ra ted at
5 A at 250 V ac non-inductive or 3 0 V dc
» dc output: » +24 V dc
» 20 mA average to 200 mA at 1/10 duty
cycle max
Communication: » RS-232 or ± 20 mA bipolar current loop,300,
600, 1200, 2400, 4800, 9600 or 19200 baud
Data Logs: » va riable rate on 1 , 5, 15, 30 or 6 0 min or 24 hr
» 31 days minimum/2 years maximum
Display: » illuminated liquid crystal 5 x 7 dot matrix
display with 2 lines of 40 characters each
Enclosure: »Type 4X / NEMA 4X / IP65
» 209 mm W x 285 mm H x 92 mm D
(8.2" W x 11.2" H x 3.6" D)
» polycarbonate
Weight: » 2.3 Kg (5.1 lb)
Approvals: » CE *, F M, C SA
NRTL/C
» MCERT S C lass 1 open channel flow device with environment
operation limits at 35 °C (95 °F) at 93% relative humidity
SIRA MC 050058/01
PROGRAMMER
Enclosure: » genera l purpose
» 67 mm W x 100 mm H x 25 mm D
(2.6 " W x 4" H x 1" D)
» ABS plastic
Operating Temperature: » –20 to 50 °C (–5 to 122 °F)
7ML19985AB01 OCM III 10
Battery: » 9 V (ANSI / NEDA 1604, PP3 or equivalent) or
3V lithium battery
TRANSDUCER
Model: » XRS-5*
Refer to associated Transducer manual.
TEMPERATURE SENSOR
Model: » TS-2 , LTS-1 or LTS-1C
Refer to associated Temperature Sensor manual.
CABLING
Transducer: » RG-62U coaxial
» maximum separation 183 m (600 ft)
» must be run in grounded meta l conduit
mA Output: » Belden 8760 or equivalent
Synchronisation: » Belden 8760
Temperature Sensor: » Belden 8760, 1 pair shielded/twisted,
Communication: » RS-232: » Belden 8770, 3 wire shielded, 24 AWG
» Bipolar Current: » Belden 9552, 2 pair shielded/twisted,
*Note: The XRS-5 must be used with the TS-2 external temperature sensor when
operating with the OC M- 3.
Velocity Input: » Belden 8760 or equivalent
7ML19985AB01 OCM III 11
18 AWG or equivalent
» maximum separation 183 m (600 ft)
» can be run in conduit with transduce r cable
or equivalent
» maximum separation 15 m (50 ft)
18 AWG or equivalent
» maximum separation 1,500 m (5,000 ft)
Auxiliary Input: » Belde n 8760 or equivalent
24 V Output: » Belden 8760
COMMUNICATION SOFTWARE
Milltronics Utilities Software on standard P C floppy disk for DO S 3 .1 a nd up.
7ML19985AB01 OCM III 12
INSTALLATION
Installation shall only be performed by qualified personnel
and in accordance with local governing regulations.
INSTALLING THE OCM-3
The OC M-3 should be mounted in a clean, dry are a that is: within the ambient
temperature range a nd suitable for the specified enclosure. The front cover should be
accessible for programming and viewing.
It is advisable to keep the OCM-3 away from high voltage or current runs, contactors
and SCR control drives.
Do not mount the OCM-3 in direct sunlight without the use of a sun shield.
This product is susceptible to electrostatic shock.
Follow proper grounding procedures.
OUTLINE AND MOUNTING
209 mm
16 mm
(0.6")
Milltronics reccomends using a punch for making
holes in enclosure. Use suita ble cable glands to
maintain ingre ss rating.
(8.2")
172 mm
(6.8")
suitable loca tion for
conduit entrances
lid screws
(6 places)
267 mm
(10.5")
mounting holes
(acce ssed under
lid 4.3 mm (0.17")
dia.,4 place s
285 mm
(11.2")
progra mmer
enclosure
customer mounting
screw
lid
106 mm
(4.2")
91 mm
Non metallic enclosure does not provide grounding between connections.
Use grounding type bushings and jumpers.
(3.6")
13 OCM III 7ML19985AB01
OCM-3 LAYOUT
board A
display
board
board B
All field wiring must have insulation suitable for at least 250 V.
Hazardous voltage present on transducer terminals during operation.
dc terminals shall be supplied from SELV source in accordance
with IEC 1010-1 Annex H.
Relay contact terminals are for use with equipment having no accessible
live parts and wiring having insulation suitable for at least 250 V.
The maximum allowable working voltage between
adjacent relay contacts shall be 250 V.
14 OCM III 7ML19985AB01
SYSTEM DIAGRAM
OCM-3
mA output
relay output
auxiliary input
velocity input
RS-232
Milltronics transducer,
see Specifications
Milltronics TS-2 ,
temperature sensor
customer device
customer alarm,
pump or control
device
customer device
customer device
customer device
bi-polar curre nt
(Milltronics communication)
Maximum system capa bility. Not a ll components or their maximum qua ntity
may be required.
15 OCM III 7ML19985AB01
Milltronics CVCC
98/03/05
INSTALLING THE TRANSDUCER
Max cable run 183 m (600 ft) of
RG-62U or equiva lent. Cable must
be run in a grounded metal conduit
with no other cabling (except
Temp. Sensor ca ble).
Ground shield at O CM-3 only.
Insulate shie ld at junctions to
prevent inadvertent grounding.
Basic Wiring – T ransducer
Hazardous voltage present on transducer terminals during operation.
Note: When using the XRS-5 transducer with the OCM-3, use the TS-2 external
temperature sensor. The internal temperature sensor in the XRS-5 cannot be used.
INSTALLING THE TEMPERATURE SENSOR
In order to compensa te for uniform
temperature change in the air
between the transducer and the flow
surface, the temperature sensor
must be connected to the OC M-3.
Maximum cable run 183 m (600 ft) of
Beldon 8760, 1 pair shielded/twisted,
18 AWG or equivalent.
Tempera ture sensor cable ca n be
run with the transducer cable in a
grounded metal conduit.
Ground shield at OCM-3 only.
Basic Wiring – Temperature Sensor
16 OCM III 7ML19985AB01
mA OUTPUT
RELAYS
isolated 0 or 4 to 20 mA output (P26) into 1 KΩ load maximum.
Wiring should conform to standard instrumentation practice s.
Ground shield at OCM-3 only.
relays shown in de- energized state ,
contacts rated at 5 A at 250 V
non-ind uctive.
n.c. com n.o. n.c. com n.o. n.c. com n.o.
All relays are certifie d for use in equipment whe re the short circuit capacity of the
circuits in which they are connected is limited by fuses ha ving ratings not exce eding
the rating of the re lays.
17 OCM III 7ML19985AB01
SYNCHRONIZATION
Where two to a maximum of twelve transducers will be sharing a common conduit the
OCM- 3s should be synchronize d. In order to synchronize OCM-3s:
» remove jumpe r J1 on board A on all but one OCM-3
» interconnect the SYNC terminal (T B1-20) of all OC M-3s. I nsure that
all O CM-3s sha re a common ground ( TB1-34 ).
18 OCM III 7ML19985AB01
POWER CONNECTIONS
The OCM-3 power supply accepts 100, 115, 200 or 230 V ac per switch SW1
(board B) se lection and 9 to 30 V dc.
The OC M- 3 operates e ither under ac or dc power, or both ac and dc live
simultaneously. If both ac and dc power are live, the OC M-3 normally draws power
from the ac supply. In the e vent tha t the ac supply fails, the OCM- 3 then draws power
from the dc supply.
AC POWER
*
* switch shown in
‘OFF ’ position,
select appropriate
voltage.
100/115/200/230 V ac, 50/60 Hz,
select volta ge via switch on board B
The equipment must be protected by a 15 A fuse or
circuit breaker in the building installation.
A circuit breaker or switch in the building installation, marked
as the disconnect switch, shall be in close proximity to
the equipment and within easy reach of the operator.
DC POWER
nega tive dc input ( TB1- 24 ) is
9 to 30 Volt
dc input
dc terminals shall be supplied from SELV source in accordance
with IEC 1010-1 Annex H.
19 OCM III 7ML19985AB01
tied to ground (TB1-3 4)
INSTALLING THE MEMORY BACK-UP BATTERY
Disconnect power before installing or replacing the ba ttery.
Do not install the memory back- up
battery until the OCM -3 is to be used.
The unit is supplied with one battery
package. Remove the battery from
the pa ckage and insert it into the
batte ry socket.
Refer to Operation \ M emory.
The memory battery, B1 (see Specifications) should be replaced yea rly to insure
memory back up during lengthy power outages. An on board capacitor provides
one hour of memory retention in order to preserve the me mory while the battery
is being changed.
COMMUNICATING VIA COMPUTER
Refer to Communication.
INSTALLING THE PROGRAMMER
To program the OCM-3 via the Programmer, it must be placed into the front cover
recess of the OCM -3. The back of the Programmer has a magne tic plate which will
hold the progra mmer in place. I t ca n be removed when programming is completed.
20 OCM III 7ML19985AB01
START UP
GENERAL
For the initial start up, it is advisable to use the programmer for programming the
OCM-3. The programmer transmits a coded infrared signal each time a key is pressed.
The OCM- 3 is designed to a utomatically scroll through the ‘A’, ‘D’, ‘F’, ‘P’ and ‘U’
paramete rs in a structured sequence. The scrolling is interactive in that, depe nding on
the option chosen for a given para meter, subseque nt parameters may be skipped or
modified. The user is thus prompted to satisfy only the pa rameters which are availa ble
to him for the application he ha s chosen.
KEYPAD
numeric
entries with
decimal point
access to ‘A’ parame ters
/ initiate s a printout while
viewing ‘Flow and Total’
access to ‘D’, ‘F ’,
‘P’ and ‘U’
paramete rs
negative
scrolls
Forward
Backward
through
through the
the parame ters / ente rs
content of entry field
scrolls
parameters / clears content of entry field
scrolls through selecte d
parameter options
7ML19985AB01 OCM III 21
LEGEND
Press the a ssociated progra mmer key:
Display shown on OCM- 3:
Programmer key:
INITIAL START UP
After installation procedures ha ve been completed, the OC M- 3 may be powered up.
Upon initial powering up, the unit momentarily displays:
and the n scrolls through the ava ilable languages:
The OC M- 3 is asking which langua ge you prefer to communicate in!
0
(0) la nguage
English
English language
selecte d
advance to ‘F0’
F0 enter security code
< - - -
7ML19985AB01 OCM III 22
8 2 8
1
72
factory set security code
2.71828 must be entered
P0 language
0 English
if the wrong language
was selected, it may
be changed here
P1 dimensional units
0centimeters
continue programming by
entering the desired options
and advancing until the
scroll returns to ‘P0’. It is
then assumed that the
user has entered all the
required paramete rs.
P0 language
0 English
For optimum calibration accuracy, an ‘F13’ should be performed prior to acce ssing
‘F2’, the normal operating mode.
3
1
F13 auto zero calibration
enter the current head. The
OCM-3 calculates ‘P46’ and
automatically ente rs the va lue.
e.g. 1 6 0
01 6
F13 auto zero calibration
160
F13 auto zero calibration
0 completed
7ML19985AB01 OCM III 23
If data logging is desired, the time and date must be set.
4
F4 24-hr. time
e.g. 1141
4
1
1
1
F4 24-hr. time
1141
11: 41 a.m.
seconds are always
assumed to be 00
,
F4 24-hr. time
11:41:00 enter new time
time is displa yed in
hh:mm:ss
F5 (ddmmyyyy) date
e.g. 12101492 October 12, 1492
0 1
4
9 211 2
F5 (ddmmyyyy) date
12/10/1492 enter new date
The start up procedure is now complete. Enter ‘F2’ to place the OCM-3 in the normal
operating mode.
2
Note: To save parameter values, return to RUN mode (F2) after programming.
The OC M-3 now displays the flow ra te and total. Refer to Ope ration \ Display
7ML19985AB01 OCM III 24
FUNDAMENTAL CHECKS
For accurate determination of flowrate, accurate head measurement is essential.
Check the following and correct if necessary.
» check D5 for correct temperature at transducer location.
» check D9 for corre ct distance from transducer to he ad.
» check D0 for accurate head measurement.
7ML19985AB01 OCM III 25
7ML19985AB01 OCM III 26
OPERATION
Upon powe r up, the transducer is fired pe riodically as se t by P36. A long interval
betwe en measureme nts may be de sirable in order to conserve power* whe n
operating the OCM- 3 from a D C source of limite d capacity.
The echo is processed to determine the head (D0). The flow rate (D1) is calculated by
the OCM-3 as a mathematical function (P3 and P4) of head or a function of head and
velocity (P42). The flow rate is then integrated to yield the totalized flow (D2). The
‘Flow’ and ‘Total’ fields which a re displayed during the norma l running mode (F2) are
also continuously updated.
Viewing or changing the content of a paramete r (except F1, e mulation) is done
without disturbing the acquisition, processing or logging of flow da ta (see \ Security).
*
restricted usage of display lighting (P14), relays (P15, 18 & 21), mA
output and communications will also conserve power.
MEMORY
During a power interruption, the memory back up will hold the programming, the log
and the totaliz er values, and run the clock. The memory battery (B1) provides up to
one ye ar of memory re tention (se e Appendices \ M aintena nce).
Note: To save parameter values, return to RUN mode (F2) after programming.
SECURITY
The content of all ‘A’, ‘D’, ‘F’, ‘P’ and ‘U’ parameters ca n be viewed without having to
satisfy the security parameter, F0. However if it is desired to change the content of
any of these pa ramete rs, the se curity para meter must be satisfied (exce pt for
resetting the running min/max displays, parameters D3/D 4 and D 6/D7).
Once security ha s been satisfied, access continue s for 5 minutes after the last key is
pressed or until F2 is re -entered.
The security code may be changed from its factory set value, 2.71828, by entering a
new value into F10. It is imperative that the new value be recorded, as the code can
not be vie wed. I f the code is lost, consult Milltronics.
UNITS
Programming of the OCM-3 involves setting the units of measure:
» P1 linear and velocity
» P2 temperature
» P5 flow rate and volume
If the units are change d during the course of opera tion, the change will be effected
through all a ssociated parameters and displa ys and will rescale flow and tota l data
stored in the logs.
7ML19985AB01 OCM III 27
FLOW CALCULATION
Absolute vs. ratiometric
The OC M-3 can be progra mmed to use e ither of two methods (P4) for calculating flow
from the head measurement: absolute or ratiometric. The result is the same
regardless of the method use d. The principal difference is the information that must
be e ntered in orde r for the OC M-3 to carry out the calculation. T he user’s choice of
method may ultimately be based upon the information which is at hand. Re fer to U
parameters for the primary element selected for a listing of the information required.
For the ratiometric me thod, it is usually sufficient that the user know the flow rate
) which occurs at maximum he ad (h
(Q
cal
On the other hand, absolute calculations require that the user enter information such
as: the physical dimensions of the primary ele ment and the constant rela ting to units
of mea sure for both linear dimensions and flow ra tes.
).
cal
e.g.
the genera l formula for flow through a single exponent primary element is:
x
Q = KH
the specific formula for flow through a 45° V-notch we ir is:
cfs = 1.03H
2.5
thus: Q = flow in cubic feet pe r second
K = constant of 1.03
H = head in feet
The absolute method is not applicable to the following:
Palmer Bowlus flume
H flume
DISPLAY
The normal display during operation is the Flow and Total Display (F2).
flow rate fie ld
relay / "no echo" field
totalizer field
status field
7ML19985AB01 OCM III 28
Flow Rate Field
Totalizer Field
flow rate
units, P5
total
multiplier, P3 2
Relay / No Echo Field
relay identification
under loss of echo
condition, "NO
ECHO" will
alternately flash
Status Field
relay sta tus : 0 = re lay de -e nergized
1 = relay energized
* = alarm state (indicated when
flashing)
The OCM- 3 provides illumination for the LCD for ea sier viewing of the display.
Illumination can be set (P 14) to be normally on or off, or a utomatic. When automatic is
selected, the lighting will automatica lly go on when ke ypad activity is sense d and the n
extinguish after 1 5 seconds of inactivity.
For battery operation, set display lighting to off or auto.
DAMPING
The OC M- 3 provides two separate da mping functions: rea ding and mA output. Ze ro
or no damping allows fastest re sponse while high or 100% provides the slowest
response. The damping is usually set to provide a re liable response without
sacrificing stability.
The rea ding damping, P13 , dampe ns only the flow rate reading of the ‘Flow and T otal’
display F2. The damping selections are: off, low, medium and high. Rela y functions
associated with flow rate respond to the dampened re ading values.
mA output damping, P27, da mpens the cha nge in the mA output. The parame ter entry
is in seconds for spanning the 0 to 100% of the mA range selected (P26). Displays
and relay functions a ssociated with the mA output respond to its
dampened value.
7ML19985AB01 OCM III 29
RELAYS
Three on board multipurpose relays are provided by the OCM-3. P15, 18 and 21 set
the respective functions for relays 1, 2 and 3. D epending on the function selected,
these para meters de termine the need and configuration of the subsequent re lay
control parameters, P16, 17 (relay 1); P19, 20 (relay 2) and P22, 23 (relay 3).
If the relay is to function as a driver for a remote totalizer or as a flow sampler contact,
the totalizer multiplier (P32) will be factored by the setpoint . Note that paramete rs
P16, P19, and P22 will default to zero. When a relay is set to totalizer (P32), you must
have the applicable parameter (P16 for relay 1, P19 for relay 2, or P22 for relay 3) set
to something othe r than zero (normally 1).
Example: For relay 1
Re lay totalize r fa ctor =
The status of e ach relay is shown in the display. Re fer to \ Flow and Total Display.
totalizer factor (P32)
relay 1 setpoint (P16)
100 (P32=5)
=
2 (P16)
= 50 units/pulse
For battery opera tion, have relays energiz ing on alarm.
mA OUTPUT
The OC M-3 provides a mA output ( TB1 -4/5) which can be a ssigned (P24 ) to
represent the measurement of flow, head, velocity or temperature. The associated
scaling, P2 5, is fa ctory set to a value of ‘0’. This provides normal scaling with respect
to the assigned measurement.
Normal scaling for representation of flow, head or ve locity is:
» 0 or 4 mA = 0
*
» 20 mA = maximum measurement value for: » P6
at maximum head
» P7: maximum head
: flow rate
» P10: velocity
at maximum head
Normal scaling for representation of te mperature is:
» 0 or 4 mA = – 40 °C
» 20 mA = 60 °C
If custom scaling is required, the 20 mA corresponding va lue ( other than 0) can be
entered into P25. The range (0 to 20 or 4 to 20 mA) and damping (see Damping) are
set via P26 and P27 respectively.
7ML19985AB01 OCM III 30
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