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This lesson covers the following topics:
Conditions
Devices
Conditions
The following table lists power conditions you should be familiar with:
Condition Description
Surge Over-voltage that lasts seconds
Spike Over-voltage that lasts milliseconds
Sag Under-voltage that lasts milliseconds
Brownout Under-voltage that lasts seconds (lights may dim)
Blackout
Complete power failure
Devices
The following is a description of devices used to prevent power problems:
Device Description
Surge suppressor A surge suppressor conditions power so that over-voltages don't reach devices.
Surge protector A surge protector protects against over-voltages by switching a device off before an over-voltage can damage it.
A power strip provides multiple power outlets from a single plug-in but is not necessarily a surge protector.
Surge protectors can be destroyed by surges and lose their ability to protect.
Consider using a surge protector with an indicator light to show whether it is working correctly.
Line conditioner A line conditioner modifies the power signal to remove noise and create a smooth alternating current (AC) signal.
Standby power supply
(SPS) A standby power supply is an offline device that switches over to provide power when an under-voltage occurs. If the switchover is not fast enough, the computer loses power.
Uninterruptible power supply (UPS) An uninterruptible power supply is an online device that is constantly providing battery power to the computer and being recharged by the wall outlet.
There are two types of UPS systems:
An online UPS constantly powers the computer from the battery.
An offline UPS powers the computer from the wall power. When the power fails, a switch inside the UPS switches to power the computer from the battery. This is the most common form of UPS.
UPS size is measured by the volt-amp (VA) rating. The capacity of the UPS determines the number of devices and how long the devices can run when power is interrupted.
When purchasing a UPS, purchase one with enough battery power to power only critical devices such as the computer and a single monitor.
To reduce the amount of power required by the UPS, do not plug non-critical devices into the UPS.
Laser printers require more power than most UPS systems are capable of providing. For this reason, you should not connect a laser printer to a UPS. If you must provide power to a laser printer, get a dedicated UPS for that device.
A UPS is designed to provide enough power to shut a system down safely during an extended power outage. Most are not intended as long-term power solutions.
The UPS connects to the power source (usually a wall socket), the computer plugs into the UPS, and the UPS is connected through a serial or USB port to the computer. Software on the computer uses this connection to monitor battery life and to detect when the regular power is lost. You can configure the software to shut the system down automatically when the battery charge reaches a certain level. You usually need to configure the following settings when working with UPS software:
Time to wait before sending a warning to clients.
Time to wait before beginning a shutdown.
Name of programs or commands to run during the shutdown.
In addition to providing power when the power is lost, most UPS systems also condition the line and remove power spikes and sags.
Most UPS devices sound an alarm when the AC power is lost. This alarm continues until AC power is restored, although many UPS devices have a switch to mute the alarm.
During certain conditions, such as an electrical storm or when the power supply is constantly going up or down, you might need to unplug the computer to protect it. Simply turning it off might still damage the components because some power remains supplied to the system. In the case of an electrical storm, keeping the system plugged in leaves it susceptible to power spikes.
Liberty gives an inexpressible Charm to all our Enjoyments. It imparts a Relish to the most indifferent Pleasure, and renders the highest Gratification the more consummately delightful. It is the Refinement of Life; it sooths and alleviates our Toils; smooths the rugged Brow of Adversity, and endears and enhances every Acquistion in their Carriage; something of grandeur and Sublimity in their Appearance, resulting from their Freedom and Independence, that is never to be met with in those dreary Abodes, where the embittering Cirumstances of a precarious Property, mars the Relish of every Gratification, and damps the most magnanimous Spirits. They can think for themselves; publish their Sentiments, and animadvert on Religion and Government, secure and unmolested.
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But in absolute Monarchies, the whole Country is overspread with a dismal Gloom. Slavery is stamp'd on the Looks of the Inhabitants; and Penury engraved on their Visages, in strong and legible Characters. To prevent Complaints, the Press is prohibited; and a Vindication of the natural Rights of Mankind is Treason. Every generous Spirit is broke and depressed: Human Nature is degraded, insulted, spurn'd, and outrag'd: The lovely Image of GOD, is defaced and disfigur'd, and the Lord of Creation treated like the bestial Herd. The liberal Sciences languish: The politer Arts droop their Heads: Merit is banished to Cells and Deserts; and Virtue frowned into Dungeons, or dispatched to the Gallies: Iniquity is exalted: Goodness trod under Foot: Truth perverted; and the barbarous Outrages of Tyranny, sanctifi4ed and adored. The Fields lie waste and uncultivated: Commerce is incumbered with supernumerancy Duties: The Tyrant riots in the Spoils of his People; and drains their Purses, to replenish his instantiate Treasury. He wages War against his own Subjects.
Does any one think the above Representation, the Result of a roving Fancy, or figur'd beyond the Life; let him take a Survey of Rome; o'er-while the Nurse of Heroes, and the Terror of the World; but now the obscene Haunt of sequestered Bigots, and effemiated Slaves. Where are not her Scipios, and Tullys, her Brutuses, and her Catos, with other Names are equal Lustre, who plann'd her Laws , and fought her Battles, during her Freedom and Independence? Alas! they are succeeded by cloistered Monks and castrated Musicians, in Subjection to a filthy old Harlot, that pretends to a Power of devouring her Mediator, and claims a Right to eat up her People. Let him survey all Italy, once the Seat of Arts and Arms, and every Thing great and valuable; now the joyless Theatre of Oppression and Tyranny, Supersitition and Ignorance. Let him behold all this; and when he has finished his Survey, then let him believe and tremble.
But far otherwise, is the Condition of a free People. Under the mild and gentle Administration of a limited Prince, every Thing looks cheerful and happy, smiling and serene. Agriculture is encouraged, and proves the annual Source of immense Riches to the Kingdom: The Earth opens her fertile Bosom to the Plough-share, and luxuriant Harvests diffuse Wealth and Plenty thro' the Land: The Fields stand thick with Corn: The Pastures smile with Herbage: The Hills and Vallies are cover'd with Flocks and Herds: Manufacturies flourish; and unprecarious Plenty recompenses the Articficer's Toil: In a Word, Nothing is seen but universal Joy and Festivity. Such is the Happiness of the People, under the blissful Reign of a good King. But do they get a Prince, whose Heart is poison'd with Regard to regal Authority,, and who vainly imagines; that the Grandeur of Princes consists in making themselves feared; and accordingly plays the devil in the Name of the Lord: They boldly assert their Rights, and call aloud for Justice; They cannot, they will not be enslaved. Sooner shall the royal Sinner have the Honour of Martyrdom, and the Lord's Anointed perish for his Iniquity, than the whole Frame of the Government be unhinged and dissolved...]
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How signal is our Happiness, in being blessed with a Prince, form'd from the friend of the Nation, and the defender of the Liberties of Europe! A Prince, who despises the Thought of placing his Grandeur in the Violation of the Laws; but is nobly ambitions of reigning in the Hearts of his People: A Prince, who invariably exerts his native Greatness of Soul, and all his inherent and hereditary Virtues, in the Support of Truth, Religion and Liberty: A Prince, in fine, unemulous of arbitrary Sway; but ardently aspiring after those brighter Trophies, that are earn'd in the Paths of Virtue and heroic Deeds; in relieving the Injured, protecting the Oppressed, and by a diffusive Benevolence, promoting the Happiness of Mankind. Long, oh long may he still adron the Throne of his Ancestors! and when the Sovereign Disposer of Events, shall at last, to the keen and universal Affliction of his People, translate him to the Possession of a Crown, eternal and incorruptible; we may presage, (which will be the only Consideration capable of alleviating our Sorrow,) the greatest Glory, and the brightest Triumphs, from his Royal Highness's eminent Virtues; whose future Reign promises the most distinguished Prosperity to the Nation; and will exhibit to Britain, a Monarch, from his benevolent Disposition, and princely Education, the Father of his People, as well as a shining Ornament to that illustrious Family, of which we will have already seen two Heroes on the British Throne; the Scourges of Tyrants, and the Assertors of Liberty.