Buckleys ST-AC Pro User manual

ST-AC Pro’
High Frequency Spark Tester
Instruction manual
Please read this manual before using the equipment
5830-0037 07/21 │ English

ST-AC Pro’
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Table of Contents
Description ......................................................................................................... 5
Technical data .................................................................................................. 5
Unpacking.......................................................................................................... 6
Safety Precautions and Symbols ..................................................................... 6
Operation........................................................................................................... 7
Calculating the test voltage............................................................................ 9
SP-02-74 test voltage formula ................................................................................... 9
Maintenance ................................................................................................... 10
Applications ..................................................................................................... 11
Insulation Testing: ..................................................................................................... 11
Gas Discharge Lamp Testing .................................................................................. 11
Ozone Production.................................................................................................... 11
Risk Assessment ................................................................................................ 12
Disposal information........................................................................................ 13
EC Declaration of conformity ........................................................................ 14
UKCA Declaration of conformity ................................................................... 14
Contact details ................................................................................................ 15
Distributor details.............................................................................................. 15
Product registration......................................................................................... 16

Instruction Manual
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ST-AC Pro’
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Description
The ST-AC Pro’ high frequency tester comprises of a lightweight, hand-held probe
connected by a cable to a portable generator.
A robust aluminium case houses the generator and its components. On the front
panel of the case there is:
● ON/OFF Indicator lamp
● Output ON/OFF/Control knob
● Handle probe connection
On the back panel of the case there is:
● Earth return socket
● Mains voltage selector switch
● IEC mains input socket
● Mains ON/OFF switch
Technical data
Operating temperature range: 0°C to +30°C
Storage temperature range: -10°c to +40°c
Supply voltage: 110/120 volts or 220/240V AC
(see rear panel of generator unit)
Supply frequency: 50Hz to 60Hz
Power consumption: 52W
Output voltage: 10 to 55KV
Output frequency: 100KHz – ring pulsed 50Hz
Net Weight: 4.05kg
Dimensions: W = 175mm H = 90mm D = 235mm
Altitude: Up to 2000m
Relative Humidity: 80% max. (non-condensing) Installation
Category: Category II (over-voltage transients)
This product has been manufactured under the controls established by a quality
management system that meets the requirements of ISO9001.

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Unpacking
The ST-AC Pro’ and the handle should be removed from their bags and be
checked for damage. If any part is damaged, the carrier and supplier should be
notified immediately. All packing material should be kept for inspection and the ST-
AC Pro’ should not be used.
The package contains the following items:
1 x Generator unit 1 x Probe handle 1 x Mains power lead
1 x Flexible probe lead 1 x Operating instructions
If any of these are missing, contact your supplier immediately.
The packaging should be retained for the future to be used if the unit needs to be
sent back for repair or needs to be stored.
Safety Precautions and Symbols
Caution, risk of danger
Caution, risk of shock
Earth return (grounding
terminal)
Read the information in this manual carefully before using the equipment.
The ST-AC Pro’ Spark Tester is intended to generate a powerful high frequency,
high voltage discharge; therefore it should only be used by responsible and
authorised personnel that have read and understood this manual.
The ST-AC Pro’ Spark tester is designed to protect the operator from receiving a
dangerous electric shock. The case is earthed and the high-voltage output is
isolated from the mains supply.
The probe should NEVER be directed at the body.
Note: The use of this equipment should be reviewed as part of the process risk assessment.
IMPORTANT: Service and repair of this product and its components MUST ONLY
be undertaken by trained, approved technicians working in full accordance
with Buckleys’ service guidelines. Failure to do so may expose the operator to
potentially lethal voltages.
Under no circumstances should anyone other than trained approved
technicians attempt to dismantle or repair this product.

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The high voltage generated by this unit is at a frequency of 100KHz, well above the
motor frequency of the human central nervous system. A serious shock is unlikely if
the probe is accidentally touched during operation, however it is likely to be
painful, and may result in localised burns. A greater risk is to those who might have
an incipient heart condition or from the reflex action when receiving a high-
frequency shock, relating to contact by the operator if working near hot surfaces
or rotating machinery. Injury could also occur if the spark reached sensitive parts of
the body (e.g. eyes).
In a reasonably ventilated room of a volume greater than 40m3, the exposure to
ozone produced by the high voltage spark is not expected to present a major risk
to health.
In a confined space situation, it is likely that ozone levels will exceed the exposure
limit and present some risk to health. This may also be the case where the user has
some particular sensitivity or a pre-existing lung condition. Under these conditions
adequate ventilation should be provided.
When in use always position the unit so that mains ON/OFF switch is easily
accessible to the operator.
Operation
IMPORTANT: We strongly advise that individuals with pacemakers, cochlea
implants or trans-dermal electronic implants - e.g. glucose monitors do not use
our high-voltage test equipment under any circumstances.
WARNING: This equipment should NOT be used in a potentially explosive
atmosphere as the high voltage WILL cause a spark and an explosion could
result.
WARNING: This equipment should not be used in damp or wet conditions, or
where the amount of conductive dust is greater than would normally occur.
Safety Warning: DO NOT USE this equipment in the event of it being immersed in
water. It must be immediately returned to Buckleys for service, calibration
and/or repair.

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Check that the operating voltage is in accordance with the available supply
voltage by reference to the voltage selector switch on the back of the generator
unit.
Connect a suitable plug (preferably fused at 3 Amps) to the mains supply cable as
follows: Brown - Live, Blue - Neutral, Green/Yellow – Earth
Ensure that the mains supply is disconnected, and then screw the flexible probe
electrode into the red end of the handle.
Set the output control knob fully anti-clockwise (Output OFF) and check that the
mains ON/OFF switch is in the OFF position. Connect the plug to the mains supply
socket and switch on. Holding the probe handle in one hand so that the probe tip
is at least 20cm from any object and switch ON the generator.
Select the output for the required size of spark by holding the probe tip close to the
4mm earth terminal on the back panel of the generator and turn the control knob
to set the required spark length.
Anticlockwise = Reduce output/output OFF;
Clockwise = Output ON/increase output
The high voltage spark should only be taken from the metal end of the flexible
probe and not from the side i.e. through the probe’s plastic covering, as the heat
of the spark may melt the plastic and could cause a fire hazard.
The output control should be adjusted for the lowest output at which an effective
test can be carried out.
The probe should always be kept moving when testing as the high frequency
output can cause localised heating in the article under test and could burn a hole
in it.
When the testing has finished, switch OFF the generator before putting down the
handle and then remove the plug from the mains supply.
WARNING: This equipment MUST be earthed
WARNING: The equipment should not be operated if any part is in a damaged
condition
WARNING: do not connect electrodes whilst the generator is connected to the
mains supply.
WARNING: The handle should not be put down whilst the unit is switched on.

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Calculating the test voltage
The test voltage needs to be high enough to find the fault but not so high as to
make one. With reference to BS EN 60052:2002 (Measurement of Voltage with
Sphere-Gaps) it can be seen that 32,000 volts will jump a gap of 1cm between
spheres of 5cm diameter. The same voltage will jump a gap of nearly 3cm
between needles. This is because the shape of the electrode affects the point at
which corona discharge starts i.e. the sharper the points on the electrode the lower
the voltage necessary for corona discharge to start.
‘Spark-over’, or complete temporary breakdown of the air between the
electrodes, will occur when the voltage is increased to cause localised
breakdown. This soon spreads throughout the whole of the inter-electrode space
and generates the required number of ions to carry the current (this may be tens of
amperes). With this sudden increase in current there is a corresponding fall in the
voltage across the electrode to a very low level.
For the thicker types of material in the range 1mm to 30mm the formula used in the
NACE Standard SP-02-74 has been found to work well in most cases.
SP-02-74 test voltage formula
Alternatively
After the test voltage has been calculated, it is necessary to check that the
voltage is not so high as to damage the material under test. The dielectric strength
is the voltage at which the material starts to break down, this is expressed in volts
per mm, normally referring to DC.
To take an example, using the above formula, a 2mm thick sheet of PVC would
require a test voltage of at least 11,180 volts.
Referring to the plastic manufacturer’s technical data, the dielectric strength of
PVC is 8,400 volts per mm. 2mm x 8,400 =16,800V, so the test voltage is not
expected to damage the material.
If the dielectric strength of the material was only 5,000 volts per mm, then the test
voltage would be too high, and this may result in damage to the part under test. In

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this case a high voltage test may still be used if tests are carried out to ensure that
the test is valid.
Make a small hole in a test piece, then with the electrode over the hole, increase
the voltage until a spark jumps the gap. Make a note of that voltage (for example,
10,000 volts) and then use a voltage half way between that and the dielectric
strength of the material (7,500 volts). Now make some more holes in the test piece,
this time at an angle, and using a 7,500V test voltage, make sure that all the faults
are detected.
The output voltage of the ST-AC Pro’ can be roughly set by dividing the test
voltage by 1700, the answer is in mm e.g. 20,000/1700 = 11.75mm. Hold the test
probe at the calculated gap from a piece of earthed metal and increase the
output voltage until the spark jumps the gap.
Maintenance
The ST-AC Pro’ has been designed so that no maintenance is required by the user.
The ST-AC Pro’ should be inspected regularly, check for damage to the unit. If
damage is found, the ST-AC Pro’ must not be used and should be returned to the
manufacturer for repair.
IMPORTANT: Service and repair of this product and its components MUST ONLY
be undertaken by trained, approved technicians working in full accordance
with Buckleys’ service guidelines. Failure to do so may expose the operator to
potentially lethal voltages.
Under no circumstances should anyone other than trained approved
technicians attempt to dismantle or repair this product.

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Applications
Insulation Testing:
The insulation to be tested should have a conductive backing, e.g. if a joint in
plastic or rubber is to be tested, it should be laid on a metal sheet. If this is not
practical, aluminium foil or copper wire can be placed behind the joint. It is
recommended that this should be earthed, although it is not necessary if the area
of the metal backing is very much larger than the area of the probe, e.g. greater
than 1000:1.
Adjust the output of the ST-AC Pro’ for the item under test (see: Calculating the test
voltage). Slowly sweep the area to be tested, looking at the probe at all times.
When a fault is passed over, the high-voltage probe discharge will change to a
single spark. Remove the probe from the surface and mark the point where the
fault was detected.
Gas Discharge Lamp Testing
The ST-AC Pro’ can be used to excite gas discharge lamps, to confirm that the
vacuum has not been lost e.g. fluorescent tubes.
The lamp/tube should not be fitted, as the high voltage could contact the fitting
and be passed into the wiring, and could damage other equipment connected to
that wiring.
Hold the probe against the glass of the lamp and increase the output voltage from
minimum, if the lamp is correctly evacuated, the lamp will glow where the probe
touches the glass.
Ozone Production
Small quantities of ozone can be produced from the high-voltage spark, useful for
chemistry lecture demonstrations etc.
NOTE: Electrode size influences the output voltage. For this reason, we recommend a
maximum size of 150mm.

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Risk Assessment
It the user’s responsibility to complete a risk assessment before using Buckleys
equipment. The following points offer some guidance but must not be assumed to
be complete or sufficient.
Personal safety
•Have all users been trained in the correct and safe use of the instruments?
•Are they aware that the instrument produces high voltages, and can give
electric shocks if used incorrectly?
•Is the instrument in good condition, undamaged? Is the instrument dry?
Are the accessories similarly in good condition, dry and undamaged?
•Is it possible to ensure that persons with pacemakers, cochlear implants or
trans-dermal implants of any kind are sufficiently far from the instrument &
test site to be safe?
•Ozone is an irritant gas which will be produced when the instrument
produces sparks – is the test outdoors, or is there sufficient, suitable
ventilation in place to ensure that this is not hazardous?
•Is the access route to the area of the test safe? Is fall protection
necessary? If so, is it in place?
•Has the instrument been properly grounded to a metallic grounding point?
Explosion & Fire Risk
•Buckleys high-voltage instruments will produce sparks - Are you certain that
there is no risk of an explosive atmosphere?
•Have all easily-ignited and/or flammable materials been removed from the
area to be tested?
EMC & RFI
•Buckleys high-voltage instruments will produce sparks which may create
interference in nearby electronic apparatus, particularly communication
and computer equipment.
•Are you certain that there is no risk of such interference causing a danger
to others – particularly medical or life support equipment?
•Are you sure that there is no risk of such interference causing costs or
inconvenience to others – eg industrial processes, measuring equipment,
scientific apparatus, domestic radio and TV?

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Other Risks
•Have you checked that there are no ongoing processes in the area (eg
below the roof you’re working on) that may be dangerous – X-ray
machines, other radiation?
•Are you certain that the instrument has not been immersed, dropped or
otherwise damaged in a way that is not obvious?
•Have you verified that the ground connection is actually grounded?
•Is the person responsible for site safety aware of / fully understanding the
testing you are going to do, and has it been reviewed in line with the site
procedures?
Disposal information
Producer registration number: WEE/HJ0051TQ
This Product must be disposed of in accordance with UK WEEE
Producer Responsibility Regulations, or in accordance with your local
WEEE guidance.
For further information on UK WEEE regulations click on:
http://www.gov.uk/government/collections/producer-responsibility-regulations
NOTE: Wherever you are intending to use equipment of this type, on your site or on a
customer’s, always obtain clearance from the company safety officer.

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EC Declaration of conformity
We, Buckleys (UVRAL) Ltd., as sole manufacturer of the apparatus listed below,
declare that the product ST-AC Pro’ High Frequency Spark Tester is
manufactured in conformity with the following directives: 2014/30/EU,
2014/35/EU and 2015/863/EU.
Date: 01/07/2021
Authorised by:
J P Hoveman
CEO, Buckleys (UVRAL) Ltd.
UKCA Declaration of conformity
We, Buckleys (UVRAL) Ltd., as sole manufacturer of the apparatus listed below,
declare that the product
ST-AC Pro’ High Frequency Spark Tester is
manufactured in conformity with the following UK legislation: Electronic
Compatibility Regulations 2016, The Electrical Equipment (Safety) Regulations
2016 and Restriction of the Use of Certain Hazardous Substances in Electrical
and Electronic Equipment Regulations 2012.
Date: 01/07/2021
Authorised by:
J P Hoveman
CEO, Buckleys (UVRAL) Ltd.

Contact details
Manufacturer: Buckleys (UVRAL) Ltd
Address: Buckleys
House
Unit G, Concept Court
Shearway Business Park
Shearway Road
Folkestone
Kent CT19 4RG, UK
Tel: [phone]
Website: www.buckleysinternational.com
Distributor details

Product registration
Thank you for choosing a Buckleys product,
we are sure it will provide you with many years
of reliable service.
Please register this product via Buckleys’
website and download the
Warranty Registration Certificate.
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To register your product, simply visit:
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... Complete the online form and click on SUBMIT.
5830-0037~ST-AC Pro’/IM/ENG/V.7-21