Not many technical books continue to be in high demand well
beyond the natural life of their author. It speaks well to the
excellent work done by Abraham Pressman that his book on
switching power supply design, first published in 1977, still enjoys
brisk sales some eight years after his demise at the age of 86. He leaves
us a valuable legacy, well proven by the test of time.
As a young teenager raised until 1964 in Casablanca, Morocco (a former
French colony), I always dreamed of having an electric guitar. Influenced by the
success of such groups as The Ventures, The Shadows (the British equivalent of
The Ventures), and, later, The Beatles, I thought that I too could one day perform
on stage. Fender guitars were my favorite, but since I could not afford even the
cheapest model, I would try to console myself by admiring the many exorbitantly
priced models displayed at a well-known music store...
There is an upward trend that human activities involve more electric power nowadays
and for years to come. And we will soon be facing shortage of electricity supply if we
rely solely on non-renewable power generation from fossil fuels such as coals.
Renewable energy generation has proven effective in meeting the demand.
Energy efficiency is finally a common sense term. Nowadays almost everyone knows that using energy more efficiently saves money, reduces the emissions of greenhouse gasses and lowers dependence on imported fossil fuels. We are living in a fossil age at the peak of its strength. Competition for securing resources for fuelling economic development is increasing, price of fuels will increase while availability of would gradually decline.
Every employee has a story at Cummins Power Generation. Some are stories of coming to work with a parent when they were young, becoming employees themselves, then watching their children as they carry on the legacy. Others tell of starting at a distributorship and moving on to one of the many Cummins Power Generation offices located around the world. Some tell of starting at a regional office, before moving to global headquarters. Others talk of their days as customers working for utility companies.
In the last chapter we introduced you to the concepts of supply and demand. In this chapter we will show you the power of supply and demand, show you how the invisible hand interacts with social and political forces to change the outcome of supply and demand analysis; and discuss how one must adjust supply and demand analysis with other issues kept at the back of one’s mind.
Khuyếch đại công suất âm thanh 4W-8W dùng TDA2005
9–18V at 1–2 A 8 W RMS/ch. at 2ohm 16V DC supply. 6W RMS/ch.at 4ohm 16V DC supply 4W RMS/ch.at 4ohm 12V DC supply 80 dBA. ~160 mV for full output ~31 dB maximum.
C7-11=2200uF 16V C8-12=220uF 25V IC1=TDA2005 J1=2 Pole Terminal Block J2-3=3 Pole Terminal Block
: MKð âm thanh 60W dùng TDA7294
Input sensitivity Input impedance Frequency response Slew rate Output power S/N ratio THD (40W into 8W) Power Supply R1=180ohm R2-3-5=10Kohm
1.3V (50W into 8W) 10K 15Hz - 100kHz 10V/uS 50W into 8W (0.
Operating / Parts Information
You must be familiar with the operation of this machine before you attempt to troubleshoot or make any repairs to it. Basic operating and maintenance procedures are described in the Operator’s Manual supplied with the machine. Keep a copy of it with the machine at all times. Use the separate Parts Book supplied with the machine to order replacement parts. If either of the documents becomes lost, please contact Wacker Corporation to order a replacement.
For this lab, you will need to compile power supply information as well as test
procedures. Observe various types of power supply form factors and characteristics. If at
any time you are unsure of the procedure, ask your instructor.
If each voltage is connected to a circuit with the same power factor and the three currents return along the
same conductor, then the vector sum of the three return currents is zero. Thus instead of three full sized
return cables, only one of smaller size is needed. If none of the load is single phase, then the neutral is not
needed at all. High voltage supplies are nearly always three phase without a neutral conductor. There is a
great economy in distribution costs if the electricity can be supplied in three phases. ...
These power ratings and currents are given for an ambient temperature of 50°C (122°F) at the factory-set switching frequency,
used in continuous operation (factory-set switching frequency of 4 kHz for ATV71H 037M3 to D15M3X and 2.5 kHz for ATV71H D18M3X
Above this factory setting, the drive will reduce the switching frequency automatically in the event of excessive temperature rise.
For continuous operation above the factory setting, derating must be applied to the nominal drive current in accordance with the curves
on page 14.
Automatic Voltage Regulator adjusts the excitation so that at the system design power factor, the voltage
is correct whatever the current. If however it adjusts the excitation to give the correct voltage at other
power factors, then two machines will not run in parallel. One can supply a huge leading current and the
other a huge lagging current. A “droop” is needed to give a lower voltage if the power factor lags by more
than the system design. This is achieved by the compounding. Faulty Compounding causes unstable
sharing of kVAr which can be quite violent....
The Soneplex E1 Quad Loop Extender (EQLX) Four-Position
Remote Chassis houses up to four EQLX modules and
optional line termination unit, power supply unit, E1 alarm
processor unit and E1 craft/performance monitoring module
at the customer premises, for termination of two protected
or unprotected optical E2 circuits (or up to eight E1s).
ADC’s solution for media conversion at the work area is simple, uncluttered and cost-effective. Traditional solutions typically
consist of an outlet optical interface, fiber jumper for connection to the media converter, a media converter on floor or
desk, and a power supply that plugs in to a wall outlet. Unlike the cluttered approach, the ADC work area solution
consists of two simple components:
• An integrated media converter with conversion circuitry behind the faceplate.
Approximately 860 utilities, or more than 25% of utilities nationally, offer green power
programs to customers. These programs allow customers to purchase some portion of their
power supply as renewable energy—almost always at a higher price—or to contribute funds for
the utility to invest in renewable energy development, such as solar installations at local schools.
The term “green pricing” is typically used to refer to these utility programs offered in regulated
or noncompetitive electricity markets.
Coincidentally, in the case of the aforementioned regulations a
STAG (STeam And Gas) cycle qualification is/was to provide about
6% of its steam generation to process. At this operating condition,
the overall performance approaches that of a conventional STAG
power generation cycle. Later in this paper, tables are provided
that define GE’s gas turbine and gas engine product
characteristics, which in turn illustrate the wide application range
and flexibility of these products to support cogeneration
Finally, electromagnetic bearings involve complex design problems to ensure that the heavy spindle, with its high inertia, does not fall and damage the magnetic bearing when power is shut off or momentarily discontinued. Therefore, a noninterrupted power supply is required to operate the magnetic bearing, even at no load or at shutdown conditions of the system. In order to secure safe operation in case of accidental power failure or support of the rotor during shutdown of the machine, an auxiliary bearing is required. Rolling-element bearings with large clearance are commonly used.
A synchronous machine is an ac rotating machine whose speed under steady state condition is proportional to the frequency of the current in its armature. The magnetic field created by the armature currents rotates at the same speed as that created by the field current on the rotor, which is rotating at the synchronous speed, and a steady torque results. Synchronous machines are commonly used as generators especially for large power systems, such as turbine generators and hydroelectric generators in the grid power supply. ...
Ozone presents difficulties. It is an important issue which may grow in importance in the
future if, as anticipated, concentrations rise, but the only acceptable way of monitoring it
at remote locations, without a power supply, is diffusion tubes. These have been used in
the ICP Forests Level 2 programme, but do not give values for peak ozone incidents,
which are believed to cause visible ozone symptoms.