High Voltage power supplies have several benefits and work effectively for industrial applications. However, there can be drawbacks to HV power supplies. For instance, electronic components can fail due to high voltages, which results in overheating. The damage can be irreversible as it adds up over time. Once the electronic components experience failure, the HV power supply will ultimately fail. High voltages can cause fatal injuries and, as such, must be solved correctly and by a professional.
23 lbs of trouble! Each Kaiser LS402 high voltage power supply weighs 23 lbs, and each one we have received for repairs has had different, nearly catastrophic failures…including components blown beyond recognition (see pics).
The problems causing this damage have varied and include:
- Internal voltage regulator failure
- Failure of the HV output coils
- Failure of the HV, High-Frequency output filter capacitors
- Failure of the internal switching power supply that set up the 24 VDC output for the Voltage regulators and the bus voltage circuit
So proč mohl vy have trouble with this high-voltage power supply? As in the case of our Midwest US laser technology customer, the reasons vary according to the age, condition, usage, and maintenance schedule for each unit. For example, all capacitors wear out over time and usage. How do you prevent high-voltage power supply failures? Preventive maintenance service, which would include replacing aging capacitors, would help lengthen the life of the power supplies.
Maintaining High Voltage Power Supplies
Cleaning switch gears can help in preventing HV power supply failures. Debris, moisture, and dust collected on the switch gears can deteriorate the protective devices and the insulation. The cleaning should be done in addition to other maintenance work like lubrication, tightening, and general inspection. Cleaning the control circuit should also be done with appropriate cleaning agents. Additionally, the circuit board can be repaired if any damage is noticed during the inspection.
A regular inspection would also help identify potential problems before they worsen. If there are damages to parts of the power supply equipment, they should be replaced or repaired depending on the level of damage.
It is also essential to keep track of the oil levels as regularly as possible. The oil level in the magnetic oil gauge should always be correct. Leakages should also be sealed immediately.
Having the electrolytic capacitors (not just the HV HF) replaced periodically will help prevent serious damage in the long run. You should determine the frequency of this type of maintenance based on whether the machine often sits idle or if it is used frequently. Have your HV power supply serviced at least every 3-4 years if it gets frequent use.
Are you hearing weird squealing sounds or resonance at high frequency? Warning! Catastrophic failure of your unit could be close at hand! If, during use, you notice any unusual voltage levels or odd sounds or the unit begins to resonate, consider this a warning that your machine is in trouble and needs service. Take it offline immediately and send it in for service before the damage is unrepairable.
Power supply repairs are usually far less than purchasing a new one, especially high voltage power supplies typically used for laser technology, such as the Kaiser LS402 pictured. Having a test fixture on-site at the repair center was invaluable, allowing the service team to test each of these Kaiser LS402 power supplies with the actual load condition it would face in use as it fires the laser.
Test fixtures like this are comprised of components used in the actual laser application and allow the technicians to confirm that the power supply is fully repaired and operational under load before returning it to the customer.
The test fixture can include operation at low, medium, and high voltage output based on the acceptable power supply range.
The test fixture can also be used to:
- Make accurate HV in-line measurements
- View and measure AC ripple & noise on DC HV
- Measure absolute HV DC to 0.25% @ 25 PPM stability
- View and measure Trise, Tfall, overshoot & settling time
- Measure & monitor signals from 35Hz to 10MHz
- View signals from DC to 20MHz
If you are searching for a repair center for your damaged power supplies or other industrial electronics, check first to see if your equipment is still under warranty. If so, contact the OEM about repairs. If it is out of warranty, contact an independent industrial electronic repair center to find out if they are a good fit for your company and your particular repair needs.
They should offer free evaluations for your damaged equipment and if needed, a free quote for repairs (no bench fees!). They should also provide repair reports if requested and a good warranty of at least one year covering parts and labor.
Contact ACS Industrial Services for All Your Industrial Repair Needs
ACS Industrial Services is an independent industrial electronic repair center providing repairs for all types of industrial electronic equipment and most all manufacturers, including power supply repairs, circuit boards, drives, servo motors, CNC equipment, encoders, monitors and touchscreens, test equipment, and much more.
Rush Service is available, and 2-Year Warranties cover most repairs. The customer service team can answer your questions and help solve your industrial electronic repair problems. You can reach them by calling 800-605-6419 or going to www.acsindustrial.com.
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Very basic question here and I’m only looking for a generic over view, but is it a too high current or a too high voltage that will damage electronics? I assume it will depend on the component in question — 1) For example if you have a working circuit with a 10V battery, fixed 5 Ohms resistance and a current of 2A. If you then swap that battery to 20V, would it be the new current of 4A that does the damage or that fact that the voltage is now 20V? Both values are higher than they should be so which factor will do the damage, both? 2) Also, if when you swapped to a 20V battery, you also increased the resistance in the circuit to 10 Ohms, could this still damage components in the circuit? The current is now the same as it was in the original (2A), but the voltage has gone from 10V to 20V, could this do damage? 3) Finally, you could take the original circuit and lower the resistance to 2.5 Ohms, now the voltage is the same (10V) as it should be, but the current has risen to 4A, I assume this could cause damage depending on the components in the circuit? Any help would be appreciated, thanks in advance. Edit — I didn’t make it very clear, I wasn’t specifically talking about damaging the resistors, I mean’t damage various components that could be in the circuit.
zeptal se 16. října 2015 v 0:57
315 2 2 zlaté odznaky 3 3 stříbrných odznaků 8 8 bronzových odznaků
$begingroup$ Heat, usually. $endgroup$
16. října 2015 ve 1:00
$begingroup$ Which is fancily called electrical overstress EOS. Now you know what to read/google. $endgroup$
16. října 2015 ve 1:21
$begingroup$ And if you want practical advice regarding how to select resistors: edn.com/design/components-and-packaging/4321070/… $endgroup$
16. října 2015 ve 2:18
$begingroup$ The different ratings (such as maximum voltage, maximum current, maximum power) are generally related to different failure mechanisms, so you need to keep all of them in mind in your design. For a similar question (specifically about connectors), see here. $endgroup$
16. října 2015 ve 2:58
$begingroup$ Resistors are hard to damage by voltage/current alone — if the stress is short enough (millisecons), you can apply hundreds of Volts (and tens of Amperes) on your 10 Ohms / 20 W resistor without any issues. If you keep the resistor under such stress, it will overheat and eventually burn out. $endgroup$
16. října 2015 ve 8:51
5 odpovědi 5
A general answer is that electronic/electrical components are damaged when their electrical ratings are exceeded. Excessive current results in excessive heat which will destroy both passive and active components. Some passive components, such as capacitors have a max voltage rating, which if exceeded can result in failure of the dielectric (insulator) resulting in excessive current, and ultimately smoke. Generally, exceeding voltage ratings of passive compnents causes insulation failure. With active components, excessive voltage will cause a breakdown of the internal junctions of the diode, transistor, etc, which will also allow excessive current, heat and some smoke. However, in these cases the current will be quite a bit lower than when passive devices are overheated. My experience is that even a small spark on a transistors leads will destroy the component. The over-voltage condition breaks down the semi-conductor junction and it does not heal. The part is now just a lump.
odpověděl 16. 2015. 2 v 34:XNUMX
96 2 2 bronzové odznaky
$begingroup$ Thanks @Wes, this is what I was looking for. To confirm, in a simple working circuit with various components, and I doubled the voltage, but also doubled the resistance so the current remained the same, this can cause damage? ..and vice versa, if I halved the resistance but kept the source voltage the same, this will double the current and can also cause damage. If I doubled the voltage but didn’t increase the resistance, then both the voltage and current will be too high and will potentially do double the damage (and the power will also double)? In simple terms, something along those lines? $endgroup$
16. října 2015 ve 3:49
$begingroup$ Also, when you say some components have a max voltage rating, does this mean that regardless of current, if you go above this value it will still potentially damage it? Even with a minuscule current in the circuit, a voltage higher than the components is rated for can cause damage/function incorrectly? Thanks. $endgroup$
16. října 2015 ve 7:27
$begingroup$ Your comment regarding the relation ship of Voltage, Current and Resistance is fundamentally correct, simple Ohm’s Law stuff. But the matter of what will cause damage is more related to the actual operational ratings of the components. If you increase the voltage applied to an operating circuits, you may see an increase in current, but not always. Some circuits are designed to self-protect and adjust to keep currents within safe values. Any change that increased current could result in damage due to excessive heat from the increased current. $endgroup$
17. října 2015 ve 4:21
$begingroup$ The matter of exceeding voltage ratings is also related to current, but in a different way. When the absolute max rating of a device is exceeded, the internal materials become conductors when they should be insulators, and now current flows in places and amounts not intended. This is commonly referred to as «Letting the smoke out». It has really nothing to do with Ohms’ law, this is just a catastrophic failure. $endgroup$
17. října 2015 ve 4:23
$begingroup$
Things like resistors will fail from excessive power dissipation- they get too hot and the materials they are made from suffer irreversible degradation. For example, the lacquer on the outside of a through-hole resistor may discolor or burn off, the resistance value change as the element oxidizes until finally it changes out of spec or opens up and starts arcing. Wires and PCB traces behave like resistors- too much current and the insulation burns off, the PCB delaminates or the trace opens up.
In low voltage circuits usually the voltage rating is not an issue- but if you were to take (say) an ordinary 0805 20M resistor and apply 2kV to it the power would be (in theory) only 200mW (which might be in spec or slightly outside of it) but the resistor could arc over and cause irreversible damage almost instantly. Similarly, you can have arcing between traces.
Things like capacitors and MOSFET gate oxide can fail when they are exposed to excessive potential which causes irreversible damage to the insulation. There will be some very localized heating (or more depending on what happens after the insulation is punctured) but that’s not the main cause.
Things like diode and transistor junctions have breakdown voltages above which the current increases rapidly with voltage (sometimes they snap on with an avalanche/negative resistance characteristic). If the current is limited to that the heating is kept to a sensible amount (and doesn’t increase too fast so that the heating is not localized to tiny areas) then this can be non-destructive. Otherwise the junctions can heat until they are not longer good semiconductor junctions any longer (in the hundreds of degrees C to destroy a silicon junction).
Getting back to your specific question about resistors- none of the voltages you mention is likely to run into a maximum voltage specification on the resistors (anything under about 25V you can forget about for resistors that are not an inhalation hazard).
So you’re left with maximum power dissipation (and maybe maximum current if the resistance value is stupidly low, but let’s ignore that). Here is a datasheet for a series of resistors, say we have a 10$Omega$ resistor 0805 size. Rated power is shown as 0.125W and maximum working voltage as 150V. If you look at the «Power Derating Curve»:
.. you can see that the rated power holds for ambient temperatures up to 70°C, but above that you must consider the rating to be less, according to the curve. Why does it level off at 70 degrees? Most likely the resistor would survive okay at >100% power if the ambient is kept cool, but the manufacturer does not want us testing that.
Recall that power dissipation of a resistor is $$P=I^2R$$ or $$P=V^2/R$$
(since power is $$Vcdot I $$ and Ohm’s law).
In your first example, the resistance is fixed and you double the voltage- so the power should go up by 4:1. (from 20W to 80W) If your resistor is rated for 80W or more (under the conditions it sees in your box) then all will be fine. Otherwise, it may not be. Damage is caused by the heating, which is the product of voltage and current (obviously the current increases protože the voltage is increased).
In your second example, you’ve doubled the resistance and the power is now 40W rather than 20W. If the resistor is rated for 40W then all will be fine.
The third example also results in 40W of dissipation. So if the resistor is good for 40W you’re fine.
