HIGH VOLTAGE REFERENCE MANUAL 1/2020 REV. 7 Copyright © 2020 Spellman High Voltage Electronics Corp. TECHNICAL RESOURCES MANUAL TABLE OF CONTENTS www.spellmanhv.com SECTION 1 WHY DO I HAVE TO PROVIDE A CURRENT FAQs High Voltage Power Supplies & Safety PROGRAMMING SIGNAL TO THE POWER SUPPLY? 13 WHY DO I HAVE TO FILL OUT A CAPACITOR CHARGING ARC/Short Circuit QUESTIONAIRE IF I’M GOING TO USE YOUR POWER SUPPLY FOR CAPACITOR CHARGING? 13 ARE YOUR SUPPLIES CURRENT PROTECTED? 4 WHY IS THE SHORT CIRCUIT REPETITION RATE WHAT ARE THE BANDWIDTH CAPABILITIES OF THE HVD SERIES OF HIGH VOLTAGE DIVIDERS? 14 OF MY LOAD SET-UP IMPORTANT? 4 WHAT IS THE DIFFERENCE BETWEEN INSTANTANEOUS SHORT WHAT IS POWER FACTOR? WHAT IS THE POWER FACTOR CIRCUIT CURRENT AND CONTINUOUS SHORT CIRCUIT CURRENT? 4 OF A SWITCHING POWER SUPPLY? 14 WHY IS ARCING AN ISSUE FOR A HIGH VOLTAGE POWER SUPPLY? 4 CAN I OPERATE A HIGH VOLTAGE POWER SUPPLY DESIGNED FOR 220VAC, SINGLE PHASE FROM A 208VAC, THREE PHASE Interfacing ELECTRICAL SERVICE? 14 WHAT KIND OF HIGH VOLTAGE CONNECTOR 5 SECTION 2 DO YOU USE ON YOUR SUPPLIES? Monoblock® Cooling, Seasoning/Warm-up and FAQ’s CAN I PROGRAM YOUR SUPPLIES WITH A COMPUTER? 5 Monoblock® Cooling Recommendations 15 Safety Monoblock® Warm-up/Seasoning Procedures 15 WHAT IS A SAFE LEVEL OF HIGH VOLTAGE? 5 Monoblock® FAQ’s WHERE CAN I OBTAIN INFORMATION ON Cooling HIGH VOLTAGE SAFETY PRACTICES? 5 DO I NEED TO ENSURE MY MONOBLOCK® STAYS COOL? WHY? 16 WHAT IS AN "EXTERNAL INTERLOCK"? WHY SHOULD I USE IT? 6 Maintenance IEEE STD 510-1983 IEEE RECOMMENDED PRACTICES FOR WHAT PERIODIC MAINTENANCE DO I NEED TO PERFORM ® SAFETY IN HIGH VOLYAGE AND HIGH POWER TESTING 6 FOR MY MONOBLOCK ? 16 Minimum Settings Technology/Terminology IS THERE A MINIMUM CURRENT AND VOLTAGE I CAN SET MY MONOBLOCK® TO? 17 WHAT IS THE DIFFERENCE BETWEEN A MODULAR SUPPLY AND A RACK SUPPLY? 8 Mounting WHAT IS THE DIFFERENCE BETWEEN ARE THERE ANY SPECIAL CONSIDERATIONS FOR THE VOLTAGE MODE AND CURRENT MODE? 8 MECHANICAL MOUNTING OF THE MONOBLOCK®? 17 WHAT IS POWER CONTROL? WHEN WOULD IT BE USED? 9 Seasoning WHAT IS FLOATING GROUND? 9 HOW OFTEN DO I NEED TO SEASON MY MONOBLOCK®? 17 WHAT IS SOLID ENCAPSULATION? 9 Dose Stability WHY IS OIL INSULATION USED? 9 HOW DOES X-RAY DOSE STABILITY RELATE TO VOLTAGE/CURRENT STABILITY? 17 WHAT IS CORONA? 10 Long Term Storage WHAT IS A VOLTAGE MULTIPLIER? 10 IS IT OK TO KEEP A MONOBLOCK® IN STORAGE, UNUSED FOR WHAT IS A RESONANT INVERTER? 10 LONG PERIODS OF TIME? 17 WHAT IS A HIGH VOLTAGE POWER SUPPLY? 10 Tube Life WHAT IS A STACK TYPE HIGH VOLTAGE POWER SUPPLY? 11 WILL THE X-RAY TUBE LAST FOREVER? 17 WHY ARE CORONA RINGS/TOROIDS/BALLS USED ON SECTION 3 HIGH VOLTAGE POWER SUPPLIES? 11 Application Notes HVPS WHAT IS BALL SOLDERING? 11 AN-01 Usage/Application WHAT DO YOU MEAN; THE OUTPUT IS “GROUND REFERENCED”? 18 POSITIVE POLARITY, NEGATIVE POLARITY, REVERSIBLE POLARITY; WHY IS THIS IMPORTANT WHEN I PURCHASE A SUPPLY? 12 AN-02 “GROUND IS GROUND”, RIGHT? WHAT YOU NEED TO KNOW 18 CAN I RUN YOUR SUPPLIES AT MAXIMUM VOLTAGE? MAXIMUM CURRENT? 12 AN-03 CAN I GET TWICE THE CURRENT FROM YOUR SUPPLY YOU WOULDN’T USE A PICKAXE FOR DENTAL SURGERY: IF I RUN IT AT HALF VOLTAGE? 12 WHEN OVER SPECIFYING A POWER SUPPLY CAN BE A BAD THING. 18 WHY IS THE FALL TIME OF YOUR SUPPLIES LOAD DEPENDENT? 12 AN-04 HOW SHOULD I GROUND YOUR SUPPLY? 12 HOW LOW CAN YOU GO? WHY SIGNAL TO NOISE RATIOS ARE CAN I FLOAT YOUR SUPPLIES? 13 IMPORTANT IN PROGRAMMING HIGH VOLTAGE POWER SUPPLIES. 19 CAN I OPERATE YOUR 220VAC POWER SUPPLIES AN-05 AT VAC 230 ? 13 "NO, YOU TOUCH IT". HVPS OUTPUT FALL AND DISCHARGE TIMES EXPLAINED. 19 TECHNICAL RESOURCES MANUAL TABLE OF CONTENTS SECTION 3 SECTION 5 Application Notes HVPS Technical Articles about HVPS & HV Electronics Power Supply Use and Application AN-06 “JUST JUMPER THE EXTERNAL INTERLOCK”? IEEE STD 510-1983 IEEE RECOMMENDED PRACTICES FOR SAFETY IN HIGH VOLTAGE AND HIGH POWER TESTING 44 WHY YOU REALLY SHOULDN’T 20 AN-07 STANDARD TEST PROCEDURES FOR WHAT’S THE VOLTAGE RATING OF RG8-U HIGH VOLTAGE POWER SUPPLIES 46 COAXIAL CABLE? 21 SPECIFYING HIGH VOLTAGE POWER SUPPLIES 57 AN-08 HIGH VOLTAGE POWER SUPPLIES FOR HOW DO I CHANGE THE POLARITY ANALYTICAL INSTRUMENTATION 61 OF THE POWER SUPPLY? 21 HIGH VOLTAGE POWER SUPPLIES FOR AN-09 ELECTROSTATIC APPLICATIONS 65 WHY DO POWER SUPPLIES TAKE TIME TO WARM UP? 22 A PRODUCT DEVELOPMENT PROCESS FOR AN-10 HIGH VOLTAGE POWER SUPPLIES 69 FIXED POLARITY, REVERSIBLE POLARITY, NEXT GENERATION IN POWER FEED EQUIPMENT 73 FOUR QUADRANT OPERATION…A SIMPLE EXPLANATION. 24 HIGH VOLTAGE POWER SUPPLY TECHNOLOGY FOR AN-11 USE IN POWER FEED APPLICATIONS 77 HIGH VOLTAGE POWER SUPPLY DYNAMIC FUNCTIONAL ROLE OF X-RAY GENERATORS IN LOAD CHARACTERISTICS 24 INDUSTRIAL APPLICATIONS 80 AN-12 THE BENEFIT OF USING A CURRENT SOURCE TO SECTION 6 POWER X-RAY TUBE FILAMENT CIRCUITS 25 Technical Articles about HVPS & HV Electronics AN-13 Research Papers ARC INTERVENTION CIRCUITRY AND DESIGN AND TESTING OF A HIGH-POWER PULSED LOAD 87 EXTERNAL SERIES LIMITING RESISTORS 26 ACCURATE MEASUREMENT OF ON-STATE AN-14 LOSSES OF POWER SEMICONDUCTORS 92 THE LIMITS OF FRONT PANEL DIGITAL METERS 26 HIGHLY EFFICIENT SWITCH-MODE 100KV, 100KW AN-15 POWER SUPPLY FOR ESP APPLICATIONS 97 3.5 AND 4.5 DIGIT METER DISPLAYS EXPLAINED 27 HIGH POWER, HIGH EFFICIENCY, LOW COST CAPACITOR AN-16 CHARGER CONCEPT AND IMPLEMENTATION 103 PARALLEL CAPABILITY OF THE ST SERIES 27 COMPARATIVE TESTING OF SIMPLE AN-17 TERMINATIONS OF HV CABLES 115 HIGH VOLTAGE POWER SUPPLY PROGRAMMING A HIGH POWER, HIGH VOLTAGE SUPPLY FOR RESOLUTION EXPLAINED 27 LONG PULSE APPLICATIONS 123 AN-18 COMPARISON OF DIELECTRIC STRENGTH OF CURRENT LOOP/ARC DETECTION CIRCUITRY 28 TRANSFORMER OIL UNDER DC AND REPETITIVE AN-19 MUTIMILLISECOND PULSES 130 KEEP IT SHORT IF YOU CAN. HIGH VOLTAGE CABLE BEHAVIOR OF HV CABLE OF POWER SUPPLY AT SHORT LENGTHS DISCUSSED 29 CIRCUIT AND RELATED PHENOMENA IEEE TRANSACTIONS AN-20 ON DIELECTRICS AND ELECTRICAL INSULATION 140 GROUNDING FOR HIGH FREQUENCY TRANSIENTS ANALYSING ELECTRIC FIELD DISTRIBUTION IN DUE TO ARCING EVENTS 29 NON-IDEAL INSULATION AT DIRECT CURRENT 146 AN-21 HOW TO CALCULATE MAXIMUM AC INPUT CURRENT 30 SECTION 7 AN-22 Applications Glossary SIMPLE VOLTAGE MODE/CURRENT MODE TESTING OF A HIGH VOLTAGE POWER SUPPLY 31 APPLICATIONS GLOSSARY 152 AN-23 SL HV OFF AND HV ON CIRCUITRY EXPLAINED 32 SECTION 8 Technical Glossary SECTION 4 Application Notes X-Ray Generators TECHNICAL GLOSSARY 159 AN-01 SECTION 9 FUNDEMENTALS OF X-RAY GENERATOR— GXR Glossary X-RAY TUBE OPTIMIZATION 33 GXR GLOSSARY 181 AN-02 COMMON X-RAY TUBE FAILURE MODES 35 TECHNICAL RESOURCES SEC.1 FAQ’S HIGH VOLTAGE page 4 POWER SUPPLIES & SAFETY ARC/SHORT CIRCUIT that limit the instantaneous discharge current to a limited level. The instantaneous short circuit current is determined by the setting of the output voltage divided by the resist- Are your supplies current protected? ance that is in series with the discharge path. The amount Virtually all of Spellman's supplies (with the exception of a of time this discharge event is present(and its rate of few modular proportional supplies) are "current protected." decay) is determined by the amount of capacitance and Current protection is accomplished through the use of a resistance present in the discharged circuit. regulating current loop, otherwise known as current mode. When a short circuit is placed upon the output of a The current mode is programmed to a regulating level via supply, there is an instantaneous short circuit current. the front panel pot or the remote current programming signal. A current feedback signal is generated inside the Once the output capacitance has been discharged, supply that drives the current meter (if there is one) and additional output current can only come from the power the remote current monitor signal. By comparing the generating circuitry of the power supply itself. To prevent current feedback signal to the current program signal, this, the power supply will sense the rise in output current the supply can limit or regulated the output current to the due to this short circuit condition and will automatically desired level. Even if a continuous short circuit is placed cross over into current mode to regulate the output current on the output of the supply, the current mode will limit to the programmed present level. the output current to the desired preset level. In summary, the instantaneous short circuit current is a Why is the short circuit repetition rate of my pulse of current that discharges the capacitance of the supply, and the continuous short circuit current is the load set-up important? current limit level set and controlled by the current mode How frequently a power supply is short circuited is an of the power supply. important parameter to specify when selecting a supply for a particular application. Why is arcing an issue for a high voltage As a rule of thumb, most of Spellman's supplies are power supply? designed to be short circuited at a 1 Hertz maximum Spellman’s high voltage power supplies are designed to repetition rate. This rating is dictated by the stored energy tolerate arcing. Individual or intermittent arcing is not prob- of the output section of the supply, and the power handling lematic; but sustained long term arcing can cause output capability of the internal resistive output limiter that limits limiter overheating issues.