Campbell Scientific PWC100 User Manual

PWC100 Present Weather

Sensor Calibrator

Revision: 3/12

Copyright © 2008-2012

Campbell Scientific, Inc.

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PWC100 Table of Contents

PDF viewers: These page numbers refer to the printed version of this document. Use the
PDF reader bookmarks tab for links to specific sections.

1. Introduction..................................................................1

2. Operation and Use....................................................... 1

2.1 Operating Guidelines................................................................................1

2.2 Initial Configuration of the PWS100 for use of the Calibrator.................2

3. PWS Calibration........................................................... 2

3.1 Installing and Connecting up the Calibrator .............................................3

3.2 Starting the Tests ......................................................................................4

4. Cleaning Guide ..........................................................10

5. Calibrator Safety Guidelines.....................................10

6. Electrical Parameters ................................................11

6.1 PWC100 Voltages and Currents.............................................................11

6.2 Earth, 0 V and Transient Protection .......................................................11

Appendix

A. Assembly Guidelines.............................................. A-1

A.1 Assembly Guidelines .......................................................................... A-1

A.2 Connector Pin Outs............................................................................. A-2

Figures

2-1. PWS100 calibration disk constants .........................................................2

3-1. The PWS100 enclosure showing the LEMO connector used by the

calibrator ..............................................................................................3

A-1. Attaching the velocity disk................................................................ A-1

A-2. Attaching the visibility disk............................................................... A-1

A-3. Attachment of the velocity calibrator ................................................ A-2

i

PWC100 Present Weather Sensor Calibrator

1. Introduction

The PWC100 is a customer field calibration validation device for the PWS100.

The PWC100 calibrator system simulates particle and visibility data for the
PWS100 allowing verification of the calibration constants held within the
system.

The following features are checked by the calibrator:

• Particle velocity

• Particle size detection

• Laser beam uniformity

• Visibility range

• Component aging

The PWC100 will give a go/no go indication of the PWS100 calibration to
show whether the instrument is within normal operating limits. If required, the
PWC100 can be used to partially recalibrate the PWS100. That method is not
described in this manual. Please contact Campbell Scientific for more details
or refer to the PWS100 manual.

2. Operation and Use

2.1 Operating Guidelines

Please ensure that there are no obstructions between the PWS sensor heads
before the tests are started.

Ambient temperature should be 20°C ± 10°C.

The test should not be performed in the following conditions:

• Do not perform the calibration when it is raining or during any other

precipitation event, such as snow, hail or drizzle.

• Do not perform the calibration when the local visibility is below

approximately 10,000 meters.

• Do not perform the calibration if there is a strong wind that could blow

debris into the sensing volume of the PWS.

The PWC100 is not suitable for long term outdoor use and is only designed to
be exposed for the duration of the calibration test. Long term exposure to
outdoor environmental conditions may cause damage to the unit.

1

PWC100 Present Weather Sensor Calibrator

Care must be taken not to drop or scratch either the velocity or visibility units
as this may cause errors that could result in tests failing when they shouldn’t.

2.2 Initial Configuration of the PWS100 for use of the Calibrator

The visibility calibration disks provided as part of the calibration kit are
individually calibrated and have a number printed on them to indicate the
measured signal in a reference instrument. Each PWS100 that is to be used
with the calibrator has to have that value entered into its configuration so that it
is referenced to the properties of that disk. Once set, the PWS100 will retain
the calibrator disk information unless the sensor is reset to its factory defaults.
The test procedure outlined in the rest of the manual can then be followed
repeatedly without changing the settings in the sensors.

For information on how to set calibration disk constants, please refer to Section

7.4.3 of the PWS100 manual. Figure 2-1 provides the screen in which the
values are shown. Please note you only need to change the constants; do not
attempt to adjust the calibration of the PWS100 if carrying out the standard test
procedure.

FIGURE 2-1. PWS100 calibration disk constants

For normal operation it is only necessary to set the visibility constant, as
printed on the disk. It is also useful to set the calibrator serial number for
reference purposes. The velocity and size constants can be left at the factory
defaults of 5.000 and 2.386 as these are fixed values for a standard calibrator.

3. PWS Calibration

The calibration check procedure can be broken up into two separate sections.
The first section comprises of visibility tests and the second velocity tests. If
only a visibility test is required, then the tests can be finished after the first
stage and the velocity tests need not be run.

It may be desirable to carry out a check of the sensor before and after cleaning
the sensor’s lenses to determine if the previous readings of the sensor were
adversely affected by dirt. This would be at the customer’s discretion.

2

PWC100 Present Weather Sensor Calibrator

3.1 Installing and Connecting up the Calibrator

• Remove the existing plastic blanking screws from their positions on the

PWS center block.

• Fix the PWC100 visibility calibrator unit to the center position on the

PWS using two of the metal countersunk fixing screws provided.

(Connector for the calibrator)

FIGURE 3-1. The PWS100 enclosure showing the LEMO connector

used by the calibrator

3

PWC100 Present Weather Sensor Calibrator

3.2 Starting the Tests

All PWC100 tests can be performed without the need to access the PWS with a
PC. Only once the tests are finished and if changes to the calibration constants
are needed, will a PC be required to change the system configuration.

If at any point the LEDs behave unexpectedly, check the status table at the end
of this section.

Step 1: Performing the visibility calibration

• Check that the PWC100 visibility calibrator unit is located correctly and

securely (refer to Appendix A for additional details).

• Connect the LEMO connector coming from the velocity unit to the LEMO

socket on the PWS (as detailed in Section 3.1). This will let the PWS
know you want to start the tests. Press the RESET/STOP button on the
PWC100. Within 10 seconds, all three LEDs should light up for
approximately 3 seconds. This indicates that the calibration unit has been
detected correctly by the PWS100 and that the LEDs are functioning
correctly.

• LED L and R should now be flashing slowly and all other LEDs should be

off.

• Once you are ready, press START.

• The test is now automated. LED L and R will stay illuminated until this

stage of the test is complete. This test will take approximately two
minutes.

• Upon successful completion of the test, LED L and LED C will be flashing

slowly, indicating that the next test is ready to be started.

4

PWC100 Present Weather Sensor Calibrator

Step 2: Performing the visibility maximum limit check

• Remove the PWC100 visibility calibration disk and place it back into its

box.

• Place blanking plug into upper sensor head as shown in diagram above.

• At this point, LED L and LED C should be flashing slowly.

• Once you are ready, press START.

• LED L and LED C will be illuminated for the duration of the test. This

test will take approximately two minutes.

• Upon successful completion of the test, LED C will be flashing slowly.

This indicates the end of the visibility test.

• Remember to remove the blanking plug from the PWS before continuing.

(This is important!)

At this point, steps three through five can be ignored if only the visibility
calibrations are required.

To view the visibility test results alone, press the RESET/DONE button. This
will jump the unit to the end of the tests and will display the results in the
normal way detailed at the end of the calibration section (this is the only stage
in the tests where pressing the RESET/DONE button will not restart the tests).

Please remember to read the final section relating to tidying up and ensuring all
screws and fasteners are returned to their original positions.

5

PWC100 Present Weather Sensor Calibrator

Step 3: Position 1: Center position

Attaching the velocity calibration unit

• Fix the PWC100 velocity calibrator unit to the center position on the PWS

using two of the countersunk fixing screws provided

• Check that the velocity calibrator is located correctly and securely.

• LED C should now be flashing slowly and all other LEDs should be off.

• Once you are ready, press START.

• The test is now automated and the disk should start rotating. LED C will

stay illuminated until this stage of the test is complete.

• Wait for the calibration disk to stop rotating. This test will take

approximately two and a half minutes.

• Upon successful completion of the test, LED L will be flashing slowly and

LED C will be turned off.

6

Step 4: Position 2: Left

PWC100 Present Weather Sensor Calibrator

• Move the calibrator into the left hand position by unscrewing the calibrator

mounting screws slightly and sliding the calibrator fully to the left. Then
retighten the screws once in position.

• Visually check that the calibrator is located correctly and securely.

• LED L should now be flashing slowly and all other LEDs should be off.

• Once you are ready, press START.

• The test is now automated and the disk should start rotating. LED L will

stay illuminated until this stage of the test is complete.

• Wait for the calibration disk to stop rotating. This test will take

approximately two and a half minutes.

• Upon successful completion of the test, LED R will be flashing slowly and

LED L will be turned off.

7

PWC100 Present Weather Sensor Calibrator

Step 5: Position 3: Right

• Move the calibrator into the right-hand position by unscrewing the

calibrator mounting screws slightly and sliding the calibrator fully to the
right. Then retighten the screws once in position.

• Visually check that the calibrator is located correctly and securely.

• LED R should now be flashing slowly and all other LEDs should be off.

• Once you are ready, press START.

• The test is now automated and the disk should start rotating. LED R will

stay illuminated until this stage of the test is complete.

• Wait for the calibration disk to stop rotating. This test will take

approximately two and a half minutes.

Final calibration results

The calibration verification has now been completed. All three of the LEDs
should be solidly illuminated indicating that the PWS100 is still within its
calibration limits.

If all three LEDs are flashing, then the calibration was found to be outside of
desired levels and further action needs to be taken.

If any of the calibration checks have failed (all three light flashing after test),
then the tests should be re-run after ensuring the disk is clean and the area
between the heads is clear of any obstructions. This should remove any chance
that the calibrator or another external factor was the cause.

8

If the PWC100 still indicates a problem, please contact Campbell Scientific for
further advice.

PWC100 Present Weather Sensor Calibrator

Step 6: Final stage

• Remember to reinstall the plastic blanking screws back into the PWS100

before leaving the site.

• If a CS215-PWS or other piece of equipment was unplugged in order to

perform the tests, then ensure it is reconnected.

• Remember to check that the blanking plug has not been left in the PWS.

• Place all calibration equipment carefully back into its correct box being

careful not to scratch the visibility disk.

Final calibration result table

Result/

LED L LED C LED R Description

LED Status

Test passed ON ON ON If all tests have passed, all

the LEDs will be illuminated
at the same time

Calibration
required

Flashing Flashing Flashing Calibration values are

suspect. Do not use the
calibration values created
from this test

Fault states during tests

If during the calibration cycle, LED C and R start flashing together, then there
has been an error either with the communications to the PWS100 or that the
disk has stalled or is unable to attain the required speed for calibration.

State LED L LED C LED R Description

Disk stalled - Flashing Flashing PWS calibrator problem

9

PWC100 Present Weather Sensor Calibrator

Quick look LED status table

Test state Left Center Right Left Center Right

Visibility test Flash Flash ON ON

Visibility maximum
range test

Velocity test position 1
(Center)

Velocity test position 2
(Left)

Velocity test position 3
(Right)

Final result states

Calibration passed ON ON ON

Calibration required Flash Flash Flash

Error conditions

Fault occurrence during
tests

Ready/complete state Running state

Flash Flash ON ON

Flash ON

Flash ON

Flash ON

Flash Flash

4. Cleaning Guide

It is important to ensure that the visibility and velocity disks are clean prior to
use. Finger prints and small quantities of dust should not impair performance
significantly, but it is highly recommended that the disks are kept clean and
care is taken to ensure the surfaces are not scratched, cracked or damaged. A
cleaning agent that does not leave a residue such as isopropyl alcohol or a
product specifically designed to clean optical equipment should be used along
with a lint free cloth.

5. Calibrator Safety Guidelines

During the velocity tests, the calibration disk will be rotated at a moderate
speed.

It is recommended that the user visually checks the disk for any cracks or
distortions on its surface. If the disk is cracked or distorted in any way, the
tests should not be performed as this may cause an incorrect result or even
damage to the calibration unit. Campbell Scientific should be contacted for
advice about any damage that may have occurred to the disk.

When performing the tests, the operator should stand more than two meters
from the calibrator. This prevents the operator from interfering with the results
by causing reflections, and keeps the operator away from the rotating disk.

10

It is also recommended that the operator stands behind the laser hood while the
PWS is active.

6. Electrical Parameters

6.1 PWC100 Voltages and Currents

PWC100 Present Weather Sensor Calibrator

General details

Standby current 29 mA 30 mA No tests running

Operating current 125 mA 150 mA Disk rotating at test

Spin up current 500 mA 700 mA Disk spinning up to

+ Volts +12 V +2 8V Main supply voltage

Nominal Max Notes

6.2 Earth, 0 V and Transient Protection

The user must ensure that the ground lug on the PWS is connected to the earth
lug on the logger or another suitable termination point. The PWC100 is
connected to this earth via the umbilical cable. This connection acts as the
discharge path for electrical transients such as static and surge. Failure to
correctly terminate this connection could lead to damage to the unit or faulty
operation.

The PWC100 is protected against external electrostatic discharges from user
contact but not lightning related surges caused by nearby strikes. Therefore, do
not leave the PWC100 connected to the PWS100 for prolonged periods in field
conditions.

speed

speed

11

PWC100 Present Weather Sensor Calibrator

12

Appendix A. Assembly Guidelines

A.1 Assembly Guidelines

The PWC100 visibility and velocity calibration disks can easily be removed for
cleaning or repair if needed.

FIGURE A-1. Attaching the velocity disk

FIGURE A-2. Attaching the visibility disk

A-1

Appendix A. Assembly Guidelines

FIGURE A-3. Attachment of the velocity calibrator

A.2 Connector Pin Outs

4: Data

3: 0 V

Connector Front View

1: 0 V

2: + Volts

A-2

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