To prevent the equipments from lightning strokes. Because the cloud is negatively charged at bottom it requires a zero or a positive potential to discharge, and it selects the ground (Zero potential) to discharge. If the Telecom Equipments are fed with positive the cloud will choose the low resistance tallest positively charged Antenna's to discharge, this could damage the entire setup of Telecom equipments. So the Telecom equipments are fed with Negative supply Voltage.
48 volts is a convenient safe voltage to use, and telephone systems use a positive earth connection to minimise electroytic damage ot cables.
The term, 'negative voltage', refers to its direction and has nothing to do with 'negative' in the 'charge' sense. It's used to indicate the direction in which a voltage is acting in relation to another voltage ('positive' if acting in the samedirection; 'negative' if acting in the opposite direction). So your question is confusing: 'negative' in relation to what?
There is no particular benefit for having a higher open-circuit (or 'no-load') voltage. In fact, an ideal voltage source would have no internal resistance and, therefore, its open-circuit voltage would be identical to its closed-circuit voltage.
The voltage adds if you connect in series (positive to negative). It stays the same if in parallel (Positive to Positive and Negative to Negative).
Negative voltage is voltage that is more negative in polarity than the ground of the circuit.AnswerSince 'voltage' is simply another word for 'potential difference', it can be neither negative or positive in the 'charge' sense! These terms can only be applied to 'potential', not to 'potential difference' (voltage).So, the terms 'positive' and 'negative', when applied to voltage, simply indicate sense or direction in which the potential difference is acting. For example, if you decide that a car battery's voltage is acting in the 'positive' sense in the charging circuit, then the alternator's voltage must then be acting in the 'negative' sense -in other words in the opposite direction to the battery.
To prevent the equipments from lightning strokes. Because the cloud is negatively charged at bottom it requires a zero or a positive potential to discharge, and it selects the ground (Zero potential) to discharge. If the Telecom Equipments are fed with positive the cloud will choose the low resistance tallest positively charged Antenna's to discharge, this could damage the entire setup of Telecom equipments. So the Telecom equipments are fed with Negative supply Voltage.
Voltage is dependent on a reference. If I have a 12 volt battery, and ground the - side, it is 12 volts to ground. If I instead ground the + side, it is -12 volts to ground. -48 volt telecom equipment is simply referenced to ground "upside down" or backwards, giving it a negative sign.
The significance of negative values of voltage and current in the digital VOM is to show the accurate and full power that a particular device or equipment has in the result.
48 volts is a convenient safe voltage to use, and telephone systems use a positive earth connection to minimise electroytic damage ot cables.
+24 volts is not normally used for telecom equipment. -48 volts is the usual value. 48 was chosen as a compromise between safety and voltage/power efficiency. Minus was chosen over plus to manage corrosion effects of cabling in underground installations.
yes.. voltage regulation can be negative
This voltage is supplied by large banks of lead-acid batteries at the central office. There are 24 cells in each battery, giving 48 volts. Grounding the positive battery terminal makes the delivered voltage negative. Batteries are used so the system can keep operating (for a period of time) during a power failure, so that emergency and other important calls can still be made.
The most likely explanation is that the equipment used to stimulate the nerves uses a DC voltage to do so.
Negative 48 volt DC voltage is simply a voltage that is negative 48 volts with respect to ground. This voltage is widely used in telecommunication systems.
1. High voltage equipment = Toaster2. Low voltage equipment = Mobile phoneBefore testing, remove the source of power. Power cord from the socket for a toaster and battery from a phone.
The term, 'negative voltage', refers to its direction and has nothing to do with 'negative' in the 'charge' sense. It's used to indicate the direction in which a voltage is acting in relation to another voltage ('positive' if acting in the samedirection; 'negative' if acting in the opposite direction). So your question is confusing: 'negative' in relation to what?
What is the significance of negative values of voltage and current?Negative values show direction and that is the significance