SAKER XFVP Medium Voltage Fiber Isolated Voltage Probe User Manual

SAKER XFVP Medium Voltage Fiber Isolated Voltage Probe

INTRODUCTION

The XFVP probe is a novel voltage probe that provides high voltage isolation via fiber optic cables. Not only is this approach advantageous from the voltage isolation point of view, but is also immune to typical radiated interferences and capacitances created when using long coaxial measuring cables. The XFVP probe was designed to minimize input capacitance as this is what hurts most high frequency measurements.

Also analog optical links are prone to slight power variations due to connector mismatches, temperature drifts and offsets. We use a proprietary algorithm to calibrate the link and cancel those. This increases overall accuracy as compared to other optical equipment and saves lots of setup time during research and testing. Moreover the XFVP probe can do “hot” calibrations with no input disconnect, which translates into saved time and increased user safety making it unnecessary to access the high voltage area during operation. Another useful feature puts in  standby or turns off the probe head from the receiver so that the user does not have to access areas that can be at high voltage during tests.

Most high-end oscilloscopes feature proprietary input connectors that force the user to choose among the supplied accessories of the scope. XFVP probe can be used in any 50Ω terminated oscilloscope. This gives developers freedom to use their favourite digital scope and reduce overall investment costs at the same time. Lastly the back of the probe head features a standard camera tripod mount thread. This makes it more convenient to place the probe inside tightly spaced cabinets or power modules and maintain proper clearance distances.

SAFETY NOTES

This product is intended to be used only by trained personnel

WARNING

Do not connect or disconnect sensor cables or attenuators in the probe head while they are connected to a voltage source to avoid the risk of shock.
Remember that all metallic parts in the probe head are at the same potential
This product is not intended for detection of hazardous voltages.
The probe head is not meant to be used as a handheld unit

CAUTION

Do not use the probe for measurements on mains circuits as it is not CAT rated.
Do not use in wet or explosive atmospheres.
Do not connect the probe or attenuators to any circuit that exceeds the probe ratings.
The probe can be floated at very high voltages, please consider all clearances before making any measurements.
Do not open the probe head or receiver, they do not contain user-serviceable parts inside.
Fiber cables can break if bent at sharp angles, take care not to trip over the fiber cable that joins both receiver and probe head.
The unit contains electrooptical components, do not shock or drop the probe onto the floor.
It is always recommended that the probe head be installed over a tripod mount and secured.
When manually positioning the probe head keep in mind the unit is physically joined to the receiver unit, moving the probe head may send the receiver into the floor.

SPECIFICATIONS

1. Specs for XFVP20 model
2. -3dB, small signal, 25Ω source
3. See user manual for more details
4. Normalized to 1V input range
5. Zero and gain cal
6. Tested with alkaline or 2600mAh NiM

1% typical

|
Receiver output| Coax cable BNC, 50Ω|
CMRR (4)| <-110dB from DC to 10MHz
-90dB at 100MHz
-65dB at 200MHz|
Output ratio probe head/receiver| 1/10| V/V
Calibration time, typical. (5)| <6| s
Max common mode voltage| 50| kV
Receiver input power| 5V, USB micro B|
Probe head batteries| 2×1.5V AA type|
Battery duration| >9h|
Battery low indication (6)| Yes|
Autozero| Yes|
Autogain| Yes|
Common mode capacitance (test site dependent)| 1.5| pF
Pollution degree (EN 61010-1)| 2, Indoor use only|
Operating temperature, probe| 0..65| ºC
Operating temperature, receiver| 0..70| ºC
ESD, EMI standards| IEC61000-4-2, 61000-4-3|
CE certification| GPSD 2001/95/EC,
EMC Directive 2014/30/EU,  RoHS2 2011/65/EU|

ACCESSORIES

External patch cables that interface the user system with the SMB connector can be made by the user. Saker recommends the use of good quality SMB connectors, for example reference R114082000 from Radiall. Please read the accessories PDF to find more about these. The unterminated SMB cable leaves freedom of choice for the user to make additional terminations. In most measurement cases a typical straight 2,54mm 2 pin header installed in  the board will make for a good enough connection

COMPATIBILITY

The XFVP probe requires an external oscilloscope with internal 50 termination. The termination is needed to provide appropriate high-frequency transmission of the signal. If the oscilloscope does not have internal 50 termination, an optional BNC terminator (code XFVPTERM) can be supplied. If the probe does not see a 50 termination it will not calibrate properly.

The bandwidth of the oscilloscope is not critical, although the higher the bandwidth the better, since modern digital scope do have a useful Hi-Res mode that can lower the measurement noise substantially. (Read the document “XFVP Probe Measurements Guide”). The same can be said about the scope ADC resolution.

XFVP PROBE CONTENTS

Each package contents must include:

• Carrying case
• XFVP probe head and receiver
• XFVP10x attenuator
• SMB unterminated cable
• Quick users guide
• Tripod
• Safety list sheet

INSTALLATION AND USE

MAKE SURE NO DANGEROUS VOLTAGE POTENTIALS ARE PRESENT WHILE INSTALLING THE PROBE HEAD IN THE DUT.

This equipment is intended to be used only by trained personnel.

PLACING THE PROBE HEAD

The probe head uses a SMB connector as its input. For mechanical stability and electrical clearance it is always recommended to install a tripod in the probe head, making sure the the tripod is mostly made of plastic and not metal.

It is recommended to leave at least 15 mm of air space around the probe for each kV that the probe is floated. Increase this distance if faster than 15kV/us slew rates in the common mode voltage are expected. The higher the spacing, the lower the common mode capacitance, which lowers the current to earth provided by the measured circuit.

Do not use the probe for measurements on mains circuits. This probe and its attenuators are not CAT rated for use on these types of circuits according to definitions of IEC/EN 61010-031.

RECEIVER-OSCILLOSCOPE CONNECTION

A BNC-BNC cable is supplied to connect the receiver to a measuring oscilloscope. Use of a good quality cable is recommended as it could affect the measurement.

Set the oscilloscope vertical scale at an appropriate scale given the conversion ratio of the XFVP and attenuator (see specifications section) in question. A 50 termination is necessary for calibration to take place successfully.

The preferred method of operation is as follows:

1. Place and secure the probe head
2. Connect the probe head to the DUT using the appropriate attenuator.
3. Connect the receiver to the oscilloscope
4. Turn on the probe head and receiver.
5. Place the unit in standby mode by shortly pressing the ON/OFF button. From this moment there is no need to approach the probe head, since it can be turned on from the receiver. Calibration also can take place while the DUT is energized.
6. Power on the DUT. When the oscilloscope and DUT are ready, take the XFVP probe out of the standby mode by shortly pressing the ON/OFF button and the press the CAL button.
7. Take measurements as needed. During interpretation of results or during adjustments to the DUT place the probe in standby again.

Do not touch the sensor head or attenuator cable and connectors while taking measurements. The probe head is not a hand-held device.

OPERATION

TURNING ON

Connect the receiver to the USB cable to power the unit. To turn on either the probe head or the receiver, press the TURN ON button until the ON Led lights. It takes a short press to turn on the units. If the probe head fails to turn on check if the batteries are dead, and replace them.

The probe head cannot be turned on remotely.

TURNING OFF

The probe head can be turned off in two ways. Either directly by pressing the TURN ON button for 1 second or remotely by turning off the receiver. In either case the ON led will turn off.

To turn off the receiver press the TURN ON/OFF button for 1 second. The ON led light will turn off. As mentioned the probe head will also turn off automatically.

STANDBY MODE

This mode will place both the probe head and receiver in a low power mode for extended battery duration of the emitter. It is recommended to use this feature every time the probe is not in use, even for shorts periods of time. Since the probe head can be set into low power mode remotely from the receiver, potentially dangerous situations where the measured system is floating at high voltage, are avoided.

To enter standby mode, press the TURN ON button shortly in either unit. The ON green led will start blinking. The other unit will also enter low power mode.

To return to normal mode press the TURN ON button shortly in either unit. Both units will resume normal operation automatically. After normal operation is resumed the ON led will light continuously.

FIBER OPTIC CONNECTIONS

DO NOT TWIST OR BEND THE FIBER OPTIC CABLE AT SHARP ANGLES. MINIMUM BENDING RADIUS IS 6 CM

The probe head unit and the receiver are connected with two fiber optic cables. These are not the same standard fiber cables as those found in a house installation. Although these cables have a 4 layer protection, be mindful that they are not as resilient as copper cables so do not bend them sharply, avoid putting tension on cables and do not pull them, especially when kinks or knots are present.

Also do not remove or bend the protective fiber optic cable boots since these protect the connectors from dust and maintain the necessary alignment for proper accuracy.

CALIBRATION

Calibration is needed to adjust the analog parameters of the fiber optic link and correct for offsets and temperature drifts in each unit. Every time the CAL button is pressed both probe head and receiver run self-test prior to calibration. It is not necessary to disconnect the probe from the measured system in order to execute the calibration.

A short blink from the CAL led indicates that calibration is required. To execute calibration, first turn on both units and then shortly press the CAL button. The CAL led will turn on. If for some reason both units cannot communicate or the scope is not 50 Ω terminated, the CAL led will blink signalling an error. The calibration process will take a few seconds. If the procedure completed successfully the CAL led will turn off, otherwise it will blink and remain in that state. In this case, check the batteries in the probe head and rerun calibration.

CALIBRATION MUST BE PERFORMED AT LEAST ONCE AFTER TURNING ON THE EQUIPMENT

WARNING REGARDING ISOLATION

  THE XFVP PROBE HEAD IS NOT A HANDHELD INSTRUMENT AND SHOULD BE CONSIDERED TO BE

Due to their non-conductive nature, the fiber optic cables provide excellent isolation between probe head and receiver. However the probe head is floating at the same potential of the measured conductor. Thus the whole body of the XFVP probe head including the metallic bayonet connectors can be at hazardous potentials.

It is advisable to install a voltage detector/indicator on the measured line that provides visual and clear indication about the presence of potentially dangerous voltages. SAKER offers the MVD and MVDZ series of medium voltage presence detectors.

LOW BATTERY CONDITION

The probe head will measure the voltage of the batteries to warn the user in case of a low battery condition. The signaling threshold has been adjusted for typical alkaline AA batteries., for other chemistries it may not work properly. A single red led is used at the receiver to display this condition.

In case of a battery low event the BATT LOW led will quickly blink one time followed by a 4 second pause in the following way:

BATTERY REPLACEMENT

The probe head unit uses standard 1.5V AA batteries, either good alkaline batteries or >2500mAh NiMh batteries are recommended. To replace the batteries open the back cover of the unit. Follow the polarity sign to replace the batteries and close the cover afterwards.

REMOVE THE BATTERIES FROM INSIDE THE EQUIPMENT IF IT IS TO BE STORED DURING MORE THAN 5 MONTHS

CARE AND MAINTENANCE

Clean only the exterior surfaces of the device using a soft cloth moistened with an alcoholic/ water solution. Do not use harsh chemicals, solvents, or abrasive cleansers. To prevent damage to the measurement system, do not expose it directly to sprays, liquids, or solvents. Avoid getting moisture inside when cleaning the exterior. Dry the probe before making any voltage measurements. The probe is not waterproof.

The fiber cables should never be disconnected. The boots in the cables protect the connectors from movement, shock and dust.

There are no serviceable parts inside the probe. Return the probe in case probe fails to meet its specs or does not operate. Opening the probe voids the warranty.

EQUIPMENT CODES

cable, x10 attenuator, 2xAA batteries, tripod, quick guide, case, USB cable. Fiber cable 2m in length available up to 15m
XFVP10-2| Same as XFVP20-2 probe but 110MHz BW

PERFORMANCE VERIFICATION

XFVP probes are shipped from Saker and both probe head and receiver are tested as a system and adjusted to meet the DC gain, offset and frequency specifications. Accuracy is automatically maintained by two internal precision voltage references and a software algorithm so there is no provision for manual user adjustment either outside or inside the probe. If the probe fails repeatedly to calibrate with a properly terminated scope, it must be returned to Saker for inspection. The recommended calibration interval for the model XFVP is two years.

Equipments needed to perform verification:

• Bench Multimeter of at least 5.5 digits, accuracy better than 0.2% at AC (at 100Hz) and DC (Keysight 34450A, 34401A, Keithley DMM6500 or similar)
• Adjustable power supply or precision voltage source (up to 25V).
• Signal generator with sinewave output (2Vrms at 100Hz).
• Banana to BNC cable (Pomona 4531 or similar)
• BNC-SMB adapter (Amphenol 242185 or similar)
• BNC-BNC cable (Caltest CT2942 or similar)
• BNC T adapter (Pomona 3285)
• 50 Ohm BNC terminator (Amphenol 202104)
• BNC to banana Jack adapter (Caltest CT2939 or similar)

Functional check

The functional check verifies the basic operation of the probe functions:

• Turn on both emitter and receiver.
• Shortly press the ON key on the receiver. Both emitter and receiver should go into standby mode.
• Shortly press the ON key on the receiver. Both emitter and receiver should go out of standby mode.
• Connect the receiver BNC output cable to a 50Ohm load (using the BNC T and 50Ohm BNC termination). Press the CAL key. After 5-6 seconds the CAL red light should turn off.

Before starting the tests

• Install new alkaline batteries in the transmitter
• Terminate the receiver with 50Ohms using the BNC T and 50Ohm termination. Turn on the probe head and receiver, press CAL.
• Wait 10 minutes before starting the tests.
  

OFFSET Verification.

This test can also be performed with a short at the SMB probe input connector.

1. Set the voltage source to 0V.
2. Measure the voltage of the voltage source with the multimeter in the mV scale.
3. Connect the voltage source to the probe head with the BNC/SMB adapter.
4. Connect the output of the XFVP to the multimeter using the 50Ohm terminator and the BNC to jack adapter.
5. Press the CAL button in the XFVP receiver.
6. The offset is the difference between the voltage measured at the voltage source and the voltage measured at the output of the XFVP probe.

Total offset error (output referred) = (VXFVP – Vsource0V/10)

Probe DC GAIN Verification.

1. Using the same setup as before, set the voltage source to 2V, measure this voltage with the multimeter and adjust it as close to 2V as possible (within 10mV max).
2. Connect the voltage source to the probe head with the BNC/SMB adapter.
3. Press the CAL button in the XFVP receiver.
4. After CAL is finished measure the output voltage of the probe.
5. Remove the input to the probe and measure the voltage present at the output (offset)

To calculate the overall DC error apply the following formula to correct first for the error in the offset.

Attenuator DC GAIN Verification.

For each attenuator available perform the following procedure:

1. Install the attenuator to test in the probe head (x2, x5 or x10)
2. Using the same setup as before, set the voltage source to 4V (for the x2 attenuator), 10V (for the x5) or 20V (for the x10), measure this voltage with the multimeter and adjust it as close as possible (within 10mV max).
3. Connect the voltage source to the probe head with the BNC/SMB adapter.
4. Press the CAL button in the XFVP receiver.
5. After CAL is finished measure the output voltage of the probe.
6. Remove the input to the probe and measure the voltage present at the output (offset)
7. To calculate the overall DC error apply the following formula to correct first for the error in the offset.
   

Probe AC GAIN Verification.

1. Using the waveform generator, set at 100Hz sinewave, 1MOhm output impedance and 2Vrms output, measure this voltage with the multimeter in ACrms and adjust it as close to 2Vrms as possible (within 10mV max).
2. Connect the voltage source to the probe head with the BNC/SMB adapter.
3. Press the CAL button in the XFVP receiver.
4. After CAL is finished measure the output voltage of the probe

To calculate the overall AC error apply the following formula to correct first for the error in the offset.

Bandwidth verification (optional)

Using a spectrum analyzer with tracking generator and at least 1GHz capability:

1. Set the output level of the tracking generator to -5dBm.
2. Set the horizontal sweep from 1MHz to 500MHz, log sweep.
3. Place a jump cable from output of tracking generator to input of spectrum analyzer.
4. Normalize the reading to obtain a flat 0dBm reading across the spectrum.
5. Connect the tracking generator to a T with a 50Ohm termination and a SMB cable that connects the input of the XFVP probe.
6. Connect a 50Ohm termination to the output BNC cable in the receiver of the XFVP. Press CAL. Calibration needs to be done with an external termination because most spectrum analyzer have AC coupling.
7. Remove this external termination and connect the output of the XFVP probe to the input of the spectrum analyzer. The average level should be about -20dBm (x10 attenuation). Find the -23dBm frequency.

#      Measurement Description                          Measurement Error        Objective

1| Probe Offset error after CAL| mV|  | <1mV
2| Probe DC accuracy after CAL| mV|  | <+-1.5%
3| Probe AC accuracy after CAL| mVrms|  | <+-1.5%
4| x2 att. DC gain accuracy after CAL| mV|  | <+-1.7%
5| x5 att. DC gain accuracy after CAL| mV|  | <+-1.7%
6| x10 att. DC gain accuracy after CAL| mV|  | <+-1.7%

CERTIFICATIONS

The XFVP probe complies with EC Directive 2014/30/EU for Electromagnetic Compatibility.

Compliance was demonstrated to the following specifications as listed in the Official Journal of the European Communities:

EC/EN 61326-1:2013 EMC requirements for electrical equipment for measurement, control, and laboratory use:

Electromagnetic Emissions: IEC/EN 55011/A1:2011 Radiated Emissions 30-1000 MHz. Class B

Electromagnetic Immunity: IEC/EN 61000-4-2:2010 Electrostatic Discharge, 4 kV contact, 8 kV air. IEC/EN 61000-4-3:2007 RF Radiated Electromagnetic Field, 10 V/m, 80-1000 MHz; 10 V/m, 1400 MHz – 2700 MHz; 3 V/m, 2 GHz – 2.7 GHz

For safety compliance the product meets the IEC 61010-1 2017 Ed. and General Product  Safety Directive GPSD 2001/95/EC.

The product and its accessories conform to the 2011/65/EU RoHS2 Directive.

DIMENSIONS

CUSTOMER SUPPORT

http://www.saker-mv.com/

References

• SAKER - Medium Voltage Measurements

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