VLF AC Hipot Series
0-40 kVac and 0-60 kVac Models
With 0.1 Hz, 0.05 Hz and 0.02 Hz Output
VLF 6022CM
(0-60kVAC, 5.5 µf)
Description
AT LAST: The Portable VLF AC Testing Solution for XLPE, PE & EPR Cables
The High Voltage, Inc. Very Low Frequency (VLF) series of AC Hipots finally
enables utilities and industry to economically AC field test cables and
electrical apparatus instead of DC testing.
What is VLF?
A VLF unit is an AC hipot with a 0.1 Hz or lower output frequency, used for
AC testing high capacitance loads. At 0.1 Hz, 600 times less power is
required to test a cable, generator, etc., than at 60 Hz and 500 times less
power than at 50 Hz. A VLF test is a go/no-go stress test. The load either
holds the test voltage or breaks down. It is the surest and easiest way to
expose defects in cables and generators.
Why VLF Hipot?
“Because DC testing can be harmful to cables and deleteriously cause
faults within the solid dielectric insulation of cables!” VLF testing exposes
cable defects while not harming good insulation.
.
Our founder and our VLF inventor Stanley G. Peschel
is demonstrating the portability of a VLF system.
System Design
A variable transformer connected to a synchronous motor via a cam
arrangement raises the voltage in a sinusoidal curve to the maximum line
voltage, then reverses direction and drives the variable transformer to zero
with the same declining sinusoidal curve.
This amplitude modulated line voltage is fed into a HV transformer/rectifier
which removes the 50/60 cycles and yields a perfect sinusoidal wave up to
the 90o or peak value. The waveshape of the 90o to 180o portion of the sine
wave is maintained by sequentially changing the bleed resistors. When the
first fixed bleed resistor exponential decay line intersects the sine wave
(~45o), a second resistor is paralleled by means of a HV relay which puts
the exponential decay curve under the sine wave until about 15o, at which
time another HV relay/resistor again puts the decay line under the Sine
wave down to zero. Since the exponential decay curves are always under
the sine wave, the power supply adds a little voltage to fill the void between
the exponential and sinusoidal curve, thus maintaining waveshape.
At 180o or zero volts the output polarity of the transformer/rectifier is
reversed. The variable transformer/cam arrangement goes through its full
cycle and the negative half of the sine wave is generated. Since polarity is
reversed at zero, there are no transients or contact arcing. The waveshaping
relays switch under voltage, however, the first one at 25kV only sees 25
milliamperes, the second one at 13 kV, 50 milliamperes. The arcing is
minimal and a 3 micron filter in the oil circulating/heat exchanger loop
removes any carbon generated.
HIGH VOLTAGE, INC. 31 Rt. 7A • P. O. Box 408 • Copake, NY 12516 • (518) 329-3275 • Fax: (518) 329-3271
E-Mail: sales@hvinc.com • Web: www.hvinc.com
High Voltage, Inc. designs and manufactures high voltage test equipment for utility and industrial applications. Also available are Very Low
Frequency (VLF) high voltage AC test sets, DC power packs, AC and DC instrumented test sets, cable fault locators and other products.
VLF AC Hipot Series
(120 kV VLF Model also available)
VLF IT!
Description
VLF-6022CM Control Panel layout
Some Benefits of HVI VLF-AC Hipots
• Smallest, lightest weight AC-VLF
Hipot available with the largest
test load ratings
• Two-piece portability
Model VLF 4022CM and VLF 6022CM are continuously adjustable 0-40 kilovolt and 0-60
kilovolt AC hipots with a 0.1/0.05/0.02 Hz sinusoidal output. The waveshape is
independent of capacitive loading and can test cables up to 50,000 feet in length.
The units are portable and operate from a conventional 120 or 230 volt electrical
service.
The test sets, depending on model, consists of a 50/75 pound controller and a
72/100 pound HV section. Interconnecting and output cables are stored in a
controller compartment. Dual, cushion grip carrying handles facilitate transport by
one or two men. Operator skill is not required.
Controls are elementary: Power ON switch, HV ON and OFF buttons, overload
breaker, output voltage knob and a single range 40 kV/60 kV peak kilovoltmeter.
For waveform viewing, a BNC output jack for oscilloscope connection is included.
The unit is rated for continuous duty operation.
A VLF test can detect cable defects at a much lower voltage than a DC
Hipot/Proof test. Also, voltage transients are much smaller with a VLF AC Hipot test
during cable failure or flashover than with a DC Hipot/Proof test. No travelling
waves are generated with VLF during testing.
The VLF AC Hipot also burns, breaks-down and conditions a cable fault much
quicker than conventional DC burners. Therefore, fault locating time is reduced with
existing thumper/radar devices.
• Simple and easy operation
• Only a 120Vac, 60Hz or
230Vac, 50/60Hz input line required
• The VLF AC Hipot does NOT generate
harmful voids in the insulation through
treeing
• Harmful space charges are NOT
injected into the dielectric during testing
• A true-sinusoidal output voltage
waveform is used
• No traveling waves are generated
during testing
• Waveshape independent of capacitive
loading between 0.01µf and
maximum load
Additional test applications
•
•
•
•
•
Rotating machinery–IEEE-433
Capacitors
Full Reel Cable
Bushings & Insulators
Transformers
Need more information on VLF?
For more information on our VLF products
and VLF testing, visit our website and
download our VLF FAQ paper, numerous
technical articles, and other VLF brochures
at www.hvinc.com
Specifications VLF - 4022CM (40 kV, 5.5µF)
Input:
Output Voltage and Frequency:
Load Rating:
Duty:
Kilovoltmeter:
Currentmeter:
Control Size and Weight:
High Voltage Tank Size and Weight:
HV Ouput Cable:
Interconnect Cable Length:
Shorting Stick:
120 V, 60Hz, 10A peak, 5A avg.
or 230 V, 50/60 Hz, 6A peak, 2.5 A avg. (F Suffix)
Sinusoidal, 0 – 40 kVac peak, 0.1, 0.05, 0.02 Hz
0.1Hz: 1.1µf or 10,000 ft. (3,048 m) of cable
0.05Hz: 2.2µf or 20,000 ft. (6,096 m) of cable
0.02Hz: 5.5µf or 50,000 ft. (15,240 m) of cable
Continuous
3.5”, Center Zero, Scaled 40-0-40 kVac peak
3.5”, Scaled 0-100 mAac & 0-6µf Load Capacitance
20” w x 11.25” d x 15.25” h, 50 lbs.
508mm w x 286mm d x 387mm h, 23 kg
14.5” w x 10.5” d x 19” h, 72 lbs.
368mm w x 267mm d x 483mm h, 33 kg
20' (6 m) RG8/U with alligator clamp
10' (3 m)
20' (6 m) Lead with alligator clamp
Specifications VLF - 6022CM (60 kV, 5.5µF)
Input:
Output Voltage and Frequency:
Load Rating:
Duty:
Kilovoltmeter:
Currentmeter:
Control Size and Weight:
High Voltage Tank Size and Weight:
HV Output Cable:
Interconnect Cable Length:
Shorting Stick:
120 V, 60 Hz, 15 A peak, 7.5A avg.
or 230 V, 50/60 Hz, 8A peak, 4A avg. (F Suffix)
Sinusoidal, 0 – 60 kVac peak, 0.1, 0.05, 0.02 Hz
0.1Hz: 1.1µf or 10,000 ft. (3,048 m) of cable
0.05Hz: 2.2µf or 20,000 ft. (6,096 m) of cable
0.02Hz: 5.5µf or 50,000 ft. (15,240 m) of cable
Continuous
3.5”, Scaled 0-60 kVac peak
3.5”, Scaled 0-100 mAac & 0–6µf Load Capacitance
25” w x 13” d x 16” h, 75 lbs.
635mm w x 330mm d x 406mm h, 34 kg
15.25” w x 11.25” d x 22” h, 100 lbs.
387mm w x 286mm d x 559mm h , 45 kg
20' (6 m) Flexible, shielded x-ray with alligator clamp
10' (3 m)
20' (6 m) Lead with alligator clamp
• Both models include a Capacitance Measurement circuit for pre-determining Cable/Load
capacitance prior to conducting the VLF Hipot test, and a Charging Current Meter. In addition,
the VLF-6022CM includes a manual test timer.
HIGH VOLTAGE, INC. 31 Rt. 7A • P. O. Box 408 • Copake, NY 12516 • (518) 329-3275 • Fax: (518) 329-3271
E-Mail: sales@hvinc.com • Web: www.hvinc.com
2000VLF/6/03