DC voltage levels:
0.7V Nominal voltage drop on normal silicon diode or similar semiconductor junction
0.8V Voltages from 0V to 0.8V are considered to be logic 0 on TTL logic IC inputs
1.25V NiCd, NiMH battery cell nominal voltage
1.5V Carbon and alkaeline battery cell nominal voltage
1.6V The voltage you normally get from a fresh alkaeline battery cell
1.8V Quite commonly used very low voltage digital circuit operating voltage (many CPU cores)
2V Lead acid battery nominal cell voltage
2V Voltages from 2V to 5V are considered to be logic 1 in TTL logic IC inputs.
3V Lithium battery nominal voltage
3.3V LVTTL logic circuits operating voltage
3.6V Typical voltage used to power cell phones (either from NiMH or Li-Ion battery pack)
4.5V operating voltage for many small electronics gargets powered from three batteries
5V TTL logic circuits operating voltage
6V operating voltage for many small electronics gargets powered from four batteries
9V Commonly used battery voltage
10V Normal control voltage limit in 0-10V and 1-10V analogue control systems (light dimming and industrial use)
12V Car battery nominal voltage
13.8V the voltage you expect to get from car 12V power when car motor is running (charging battery)
24V Truck battery.
24V Automation systems most common nominal voltage used for logic signals and and current loop powering
24V common standard input voltages in Avionics and Defense applications
28V Maximum battery charging voltage for 24V battery system (for example batteries that power automation systems).
28V common standard input voltages in Avionics and Defense applications
36V Battery voltage used on some electric golf carts, electric scooters, electric bikes, high power cordless tools etc..
42.4V Voltages must be less than or equal to 42.4V peak/60V dc to meet safe limits and to be SELV.
42.4V Hazardous Voltage is a voltage exceeding 42.4V peak or 60V d.c., existing in a circuit which does not meet the requirements for either a Limited Current Circuit or a TNV Circuit.(IEC 60950)
48V Battery backed up -48V voltage is used on telecom systems for powering telephone exhanges and other telco equipment. The normal service voltage range for the -48 Vdc nominal supply at interface “A” shall be -40,5 Vdc to -57,0 Vdc according to ETSI EN 300 132-2
48V Some data centers use 48V DC to power servers (battery backup easy)
48V Phantom power feed for microphones in audio mixers most often uses +48V phantom power voltage
48V some automation systems use +48V power for equipment and I/O (electrical power distribution)
50V Work on energized circuits or apparatus below that voltage requires no “Hazard/Risk Evaluation.” NFPA 7OE
60V Voltages must be less than or equal to 42.4V peak/60V dc to meet safe limits and to be SELV.
60V Hazardous Voltage is a voltage exceeding 42.4V peak or 60V d.c., existing in a circuit which does not meet the requirements for either a Limited Current Circuit or a TNV Circuit.(IEC 60950)
72V standard input voltage in rail applications
75V Low Voltage Directive is effective for voltages in range 50 – 1000 volts a.c. or between 75 and 1500 volts d.c
110V Seen on electrical power distribution control automation as IO voltage and for operating actuators on high voltage power distribution stations.
110V standard input voltage in rail applications
120V Extra-low voltage high limit is 120 V ripple-free d.c.
125V Commonly used insulation resistance testing voltage used for low voltage wiring testing where 250V test voltage is too much.
160V The highest DC voltage covered by the telephone/telecom/ITE industry is 160V (ANSI T1.311)
169V The peak voltage on 120V AC mains power is around 169V, you get around this voltage if you rectify and filter 120V mains power
220V Seen on electrical power distribution control automation as IO voltage and for operating actuators on high voltage power distribution stations.
250V Commonly used insulation resistance testing voltage. Tests on SELV and PELV circuits are carried out at 250 V.
270V common standard input voltages in Avionics and Defense applications
324V The peak voltage on 230V AC mains power is around 324V, you get around this voltage if you rectify and filter 230V mains power
380V DC power voltage for DC feed used on some data centers. Emerge Alliance pushes using this 380V system.
500V Commonly used insulation resistance testing voltage. Insulation tests at normal mains wiring (230V) is commonly tested with 500V test voltage. Minimum insulation resistance expected on mains circuit is 0.5 Mohm. Also test between SELV and PELV circuits and the live conductors of other circuits must be made at 500 V.
575V DC power voltage for DC feed used on some data centers
600V Voltage used on third rail powered locomotive systems and overhead lines for older trams
750V Voltage used to power trains in Helsinki subway (third rail powering) and also used in modern tram systems
1000V Commonly used insulation resistance testing voltage for circuits that operate above 500 V up to 1000 V.
1500V Low Voltage Directive is effective for voltages in range 50 – 1000 volts a.c. or between 75 and 1500 volts d.c
2500V Commonly used insulation resistance testing voltage
3250V Use 2300V rms or 3250V dc test voltage for dielectric-withstand test for double insulation
5000V Commonly used insulation resistance testing voltage when testing high voltage wiring
62 Comments
Tomi Engdahl says:
https://hackaday.com/2024/10/05/why-electric-trains-sound-the-way-they-do/
Tomi Engdahl says:
Ultimate Guide to LiFePO4 Voltage Chart (3.2V, 12V, 24V, & 48V)
https://www.jackery.com/blogs/knowledge/ultimate-guide-to-lifepo4-voltage-chart
Tomi Engdahl says:
What is the safe limit of DC voltage for humans to touch?
https://www.quora.com/What-is-the-safe-limit-of-DC-voltage-for-humans-to-touch
The safe limit of DC voltage for human contact can vary based on several factors, including the individual’s health, environmental conditions, and the duration of exposure. However, general guidelines suggest the following:
Below 50 Volts: Generally considered safe for most people under dry conditions. Touching voltages below this level typically does not cause a harmful electric shock.
50 to 100 Volts: This range can be hazardous, especially in wet conditions. Although many individuals may not feel a shock, there is a risk of injury, particularly if the skin is wet or if the person has a lower resistance (due to moisture or other factors).
Above 100 Volts: Voltages above this level can pose significant risks, including serious injury or fatality. The likelihood and severity of electric shock increase with higher voltages.
Factors Influencing Safety:
– Skin Condition: Dry skin has higher resistance than wet skin.
– Path of Current: The path the current takes through the body can affect the severity of a shock.
– Duration of Contact: Longer contact times increase the risk of injury.
In summary, while 50 volts is generally considered a safe threshold, caution should always be exercised, and safety measures should be in place when working with or around electrical systems.
Which is More Dangerous AC or DC?
https://www.electronicsforu.com/technology-trends/learn-electronics/ac-dc-current-body-dangerous
Tomi Engdahl says:
Can tram electric lines kill you? I know they’re 650V or 750V DC opposed to 22000V – 25000V AC on the train systems, and that the kill factor depends on the current.
https://www.quora.com/Can-tram-electric-lines-kill-you-I-know-theyre-650V-or-750V-DC-opposed-to-22000V-25000V-AC-on-the-train-systems-and-that-the-kill-factor-depends-on-the-current
VOLTAGE IS PROPORTIONAL TO CURRENT[1]
So let’s have no more of this nonsense about how voltage isn’t really dangerous as long as the current is low. The two are proportional.
The bad explanation comes up as a way to explain why you don’t get killed when you rub your feet on a carpet and touch a doorknob. It’s only sort of correct in this situation, but it cannot be extended to “don’t worry about the voltage”.
When you touch a doorknob with a few thousand volts of electrical potential, the voltage drops to zero in a microsecond. It’s the short duration of the current that makes it harmless.
Here’s the problem: A car battery can put out 600 Amps (and it does, when starting the car). But it’s not going to kill you unless you get your tie caught in the drive belt. A household outlet can be just sitting there doing nothing, and your ammeter shows zero amps. It can absolutely kill you.
A person who learned “Volts tickle; Amps kill” would be ignorant of both of these facts, and would have no idea what was dangerous and what was not. It’s incorrect (Volts and amps are proportional!) and its dangerous. I wish people would use the saying “Amps Tickle; Joules Kill” instead.
And to answer your question, yes, a 650-volt tram line can kill you.
Yes, lower voltage dc systems (like the systems used on the London Underground, and south east England) which operate at 630–750v still has the potential to make you smoke! DC makes you more likely to grip as the current makes your muscles tense, and will stop your heart, AC gives the potential to release, however disturbs the beat of your heart, which is much more serious than a heart that has stopped!
Tomi Engdahl says:
What is the lethal voltage in DC?
This is known as the “let go threshold” and is a criterion for shock hazard in electrical regulations. The current may, if it is high enough, cause tissue damage or fibrillation which can cause cardiac arrest; more than 30 mA of Ahttps://en.wikipedia.org/wiki/Electrical_injuryC (rms, 60 Hz) or 300–500 mA of DC at high voltage can cause fibrillation.
https://en.wikipedia.org/wiki/Electrical_injury
Tomi Engdahl says:
https://endless-sphere.com/sphere/threads/is-dc-more-lethal-than-ac-why.15355/
Tomi Engdahl says:
https://diysolarforum.com/threads/how-dangerous-is-dc-compared-with-ac.38864/
Tomi Engdahl says:
https://forums.mikeholt.com/threads/dc-current-safety-threshold.136674/
Actually, it depends on the frequency. 50-60 Hz is the most dangerous, requiring about half as much current as DC to inflict the same harm. 400 Hz is about equally dangerous as DC. and increasing frequencies are increasingly less dangerous.
Tomi Engdahl says:
https://www.daicel.com/safety/en/pyrofuse/
Eco-friendly electric vehicles (EV, HEV, PHV) have rapidly penetrated the market as social awareness towards environmental protection increased over the years.
EVs equipped with high-voltage battery requires anti-electrification and secondary disasters in case of traffic accidents and malfunctions.
Daicel Safety Strategic Business Unit(SBU)s’ Pyro-Fuse enables safe, instantaneous shutdown of high-voltage electric currents.
Pyro-Fuse could also be utilized not only for EVs but also any industrial applications in need of instant circuit isolation.
What is Pyrofuse in car?
https://www.asbeam.com/news/pyrofuse_in_car-cn.html
What is a Pyrofuse and what does it do?
A Pyrofuse, also known as a Pyroswitch or Pyrotechnical Safety Switch (PSS).
So, what exactly does this device do? The primary function of a Pyrofuse is to act as a switch. In the event of a collision, short circuit, or other safety faults, the Pyrofuse can cut off the power in a very short time, reducing the probability of danger.
Currently, Pyrofuses are used in battery systems, which reminds me of BMW’s SBT. BMW’s Safety Battery Terminal activates upon detecting a collision signal, using an explosive charge to disconnect the battery terminal, thus cutting off the power supply close to the battery to prevent short circuits and fires. However, not all vehicles are equipped with this device. It is mainly found in high-end vehicles, sports cars, and electric vehicles, such as BMW, Porsche, and Tesla. Pyrofuses are typically installed near the battery or high-voltage battery, but their locations can vary, requiring special attention during vehicle appraisals.
Tomi Engdahl says:
Tesla Pyrofuse – Let’s Blow It Up!
https://www.youtube.com/watch?v=nmBdLG40wts
Tomi Engdahl says:
[EN] Pyrotechnic fuse replacement on a Tesla Model S | Masters of Motion
https://www.youtube.com/watch?v=nosz4Miz-yk
Tomi Engdahl says:
https://auton.fi/kaapelin-mitoitus/