Can I float your high voltage power supplies?

spellman's standard products are for the most part, designed and intended for use as ground referenced power supplies. that is, only one high voltage output connection is provided, while the current return path is made via the customer-provided ground referenced load return wiring. this load return …

Can I get twice the current from your supply if I run it at half voltage?

most of our unmodified products (with the exception of several x-ray generators) obtain maximum rated power at maximum rated voltage and maximum rated current. where more current is needed at lower voltages, we can provide a custom design for your particular application. please contact our sales dep…

Can I Operate a high voltage power supply designed for 220Vac, single phase from a 208Vac, three phase electrical service?

the simple answer is yes, if you connect any two phases of the 208vac electrical service to the two ac input wires (solid brown and solid blue) you can operate the power supply. connect the green/yellow wire to ground and ground the power supply properly along with making the required load return co…

Can I Operate Your 220Vac Power Supplies at 230Vac?

the simple answer is yes… in most cases you can. 220vac ±10% ranges from a low of 198vac, and to a high of 242vac. 230vac ±10% ranges from a low of 207vac to a high of 253vac. the “low end” of 230vac -10% is 207vac; this is inside the normal range of 220vac -10% (which is 198vac), so there’s no prob…

Can I run your power supplies at maximum voltage? Maximum current? How much should I de-rate your supplies?

spellman standard supplies can be run at maximum voltage, maximum current, and maximum power continuously with no adverse affect on performance or reliability. each supply we sell is burned in at full rated voltage and full rated current for a minimum of 12 hours. all of our supplies are designed to…

How should I ground your supply?

grounding is critical to proper power supply operation. the ground connection establishes a known reference potential that becomes a baseline for all other measurements. it is important that grounds in a system are low impedance, and are connected in such a way that if currents flow through ground c…

Positive polarity, negative polarity, reversible polarity; why is this important when I purchase a supply?

dc sources are polarity specific. using earth ground as a reference point, the output of a dc supply can be "x" number of volts above ground (positive polarity) or "x" number of volts below ground (negative polarity). another way of explaining this, is as a positive supply can source (provide) curre…

What are the bandwidth capabilities of the HVD Series of High Voltage Dividers?

the hvd series of high voltage dividers are intended for dc high voltage measurements only. these dividers are fabricated with only resistive elements. the parasitic capacitive effects on the divider assembly make the ac capability of the hvd basically unspecified. only dc conditions can be accurate…

What is power factor? What is the power factor of a switching power supply?

power factor is the ratio of the real power to apparent power utilized. it is typically expressed as a decimal number less than 1. real power is expressed in watts while apparent power is expressed in va (volt-amperes). the power factor of a switching power supply depends upon what type of ac input …

Why do I have to fill out a capacitor charging questionnaire if I’m going to use your power supply for capacitor charging?

a dc high voltage power supply can address some capacitor charging applications, but not all. when charge repetition rates exceed once per second or so, an application specific cap charger product is often required. if a standard dc power supply is subjected to a high repetition rate, it is possible…

Why is the fall time of your supplies load dependent?

a high voltage power supply's output section is capacitive by design. this output capacitance gets charged up to the operating voltage. when the supply is placed in hv off or standby (or turned off entirely) this charged output capacitance needs to be discharged for the output voltage to return back…

Linear versus Switch Mode Power Supplies

linear high voltage power supplieslinear power supplies were the dominant technology up until the late 1970’s. a linear power supply makes uses a series pass transistor to function as a variable resistor as the main method of regulating the output of the power supply. when full output is required fr…

Voltage Mode/Current Mode. Why a power supply can only regulate only one of these parameters at a time.

most of spellman’s high voltage power supplies offer voltage mode and current mode with automatic crossover, dependent upon settings and load conditions. this requires the power supply to have two regulating loops: voltage mode and current mode. additionally, each loop requires a programing signal p…

What is a “stack” type high voltage power supply?

the sls is a subcategory of spellman’s sl series, which offer output voltage from 160kv to 360kv (and beyond via special order) via a separate high voltage assembly commonly referred to as a “stack”. the necessity of the stack is simple, as output voltages increase economical and reliable cable/conn…

What is a High Voltage (HV) Power Supply?

high voltage power supplies are complex power conversion circuits that convert a lower voltage potential to a higher voltage potential. typical output voltages for high voltage power supplies are 1kv to 360kv, although ranges of 62v to 500kv are offered. spellman’s range of output power spans …

What is a resonant inverter?

resonant inverter is the generic name for a type of high frequency switching topology used in many of spellman's supplies. resonant switching topologies are the next generation of power conversion circuits, when compared to traditional pulse width modulation (pwm) topologies. resonant-based supplies…

What is a voltage multiplier?

a voltage multiplier circuit is an arrangement of capacitors and rectifier diodes that is frequently used to generate high dc voltages. this kind of circuit uses the principle of charging capacitors in parallel, from the ac input and adding the voltages across them in series to obtain dc voltages hi…

What is an electrical corona?

corona is a luminous, audible discharge that occurs when there is an excessive localized electric field gradient upon an object that causes the ionization and possible electrical breakdown of the air adjacent to this point. corona is characterized by a colored glow frequently visible in a darkened e…

What is Ball Soldering?

ball soldering is a soldering technique frequently used in the high voltage industry. large spherical balls of solder are used to make solder connections that are typically "at high voltage". the large diameter, smooth spherical shape of the solder connection helps to control the local e-field…

What is floating ground?

the term floating ground (fg) is used to describe an option that allows for very accurate ground referenced load current measurements to be made. whatever current flows out of the high voltage output of a supply, must return via the ground referenced return path. this current must return back to its…

What is power control? When would it be used?

power control, (a.k.a. power mode or power loop) is a third control mode that can be added to a variety of spellman supplies to provide another means to control and regulate the output of the supply. voltage mode and current mode are the primary controlling modes of most units. taking the voltage an…

What is solid encapsulation?

solid encapsulation, also referred to as "potting," is an insulation media used in a variety of spellman's supplies. the "output section" of a high voltage power supply can operate at extremely high voltages. the design and packaging of the high voltage output section is critical to the functionalit…

What is the difference between a modular power supply and a rack supply?

modular supplies and rack supplies are the two generic categories into which spellman's standard products typically fall. these product categories were created and used to help classify hardware. additionally, spellman provides a variety of custom and oem supplies that would not adequately fit into …

What is the difference between voltage mode and current mode?

voltage mode and current mode are the two regulating conditions that control the output of the supply. most applications call for a supply to be used as a voltage source. a voltage source provides a constant output voltage as current is drawn from 0 to full rated current of the supply. in these appl…

Why are corona rings/toroids/balls used on high voltage power supplies?

spellman makes high voltage dc power supplies with output voltage up to and beyond 360kv. at these extreme high voltages the physical geometry of the surfaces at high voltage becomes a critical consideration with respects to suppressing the generation of corona. corona is a luminous, audible dischar…

Why do I have to provide a current programming signal to the power supply?

spellman’s power supplies have two regulating loops, voltage mode and current mode. most people use our power supplies as a voltage source, controlling and regulating the output voltage in voltage mode. the current loop of the power supply will limit the current drawn during a short circuit conditio…

Why is oil insulation used?

spellman has invested in and developed the use of oil insulation technology, giving its engineers and designers, when appropriate, another method of high voltage packaging technology. oil, as an insulating media has some distinct advantages in particular situations. this capability has been utilized…

What is a safe level of high voltage?

safety is absolutely paramount in every aspect of spellman's high voltage endeavors. to provide the maximum margin of safety to spellman's employees and customers alike, we take the stand that there is no "safe" level of high voltage. using this guideline, we treat every situation that may have any …

What is an "external interlock"? Why should I use it?

an external interlock is a safety circuit provided for customer use. most interlock circuits consist of two terminals provided on the customer interface connector. a connection must be made between these two points for the power supply to be enabled into the hv on mode. it is strongly recommended th…

Where can I obtain information on high voltage safety practices?

one of the most comprehensive publications regarding high voltage safety practices is an excerpt from ieee standard 510-1983 known as "the ieee recommended practices for safety in high voltage and high power testing." this information is available by clicking here.

Can I program your supplies with a computer?

yes, spellman supplies can be programmed and controlled with a computer. most of spellman's newer product releases come complete with our integrated sic option which provides the ability to program the unit via rs-232, ethernet or usb protocols. many of our standard products that do not show the sic…

What do you mean that the output side of the high voltage cable on most standard products is “unterminated”?

typically, spellman uses either a fly wire or detachable high voltage output cable to provide access to the high voltage power supplies output. a fly wire is mechanically captive to the unit, making replacement not possible. detachable high voltage output cables allows for the simple exchange or rep…

What kind of high voltage connector do you use on your supplies?

while most spellman supplies typically come with one of two types of spellman designed high voltage connector or cable arrangements, many other industry standards (alden, lemo,kings, etc.) or custom cable/connectors can be provided. many of our lower power modular supplies are provided with a "fly w…

Are your high voltage supplies current protected?

virtually all of spellman's supplies (with the exception of a few modular proportional supplies) are "current protected." current protection is accomplished through the use of a regulating current loop, otherwise known as current mode. the current mode is programmed to a regulating level via the fro…

What is the difference between instantaneous short circuit current and continuous short circuit current?

the output section of a typical high voltage power supply is capacitive, which causes it to store energy. when a short circuit is placed on the output of a supply, the energy stored in the capacitance of the multiplier is discharged. the only limit to the magnitude of short circuit current is the re…

Why is arcing an issue for a high voltage power supply?

spellman’s high voltage power supplies are designed to tolerate arcing. individual or intermittent arcing is not problematic; but sustained long term arcing can cause output limiter overheating issues. spellman’s high voltage output sections are capacitive by nature. to limit the current that flows …

Why is the short circuit repetition rate of my load set-up important?

how frequently a power supply is short circuited is an important parameter to specify when selecting a supply for a particular application. as a rule of thumb, most of spellman's supplies are designed to be short circuited at a 1 hertz maximum repetition rate. this rating is dictated by the stored e…

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