The paper describes a new Windows based communication package which enables
standard Windows applications such as Excel and Access, and user designed
applications written in object orientated programming languages, such as Visual
Basic, to communicate with transducers and actuators via a fieldbus such as P-NET,
together with other standardised fieldbus types.
The paper includes examples of a simple Visual Basic programs, which display
and control field variables on a PC screen using P-NET transducers and
transmitters
DSSS Receiver Using Simulink and Hardware Optimization
Archive for March, 2009
Fieldbus Connection in The Visual Basic
Tuesday, March 31st, 2009Rotating Electrical Machines
Monday, March 30th, 2009Most people, not only in the industrialized countries, are very dependent in their daily lives on the existence of rotating electrical machines
Rotating electrical machines are very important in all sectors of the modern society. For infrastructure, industry, service functions and for the domestic sector. The development has been fascinating and new applications and
requirements still continue to push the technology further. A brief review, mainly based on the development in a small, industrialized country as Sweden will be presented and some conclusions discussed
Rotating Electrical Machines
Electric Power Generation
Tuesday, March 24th, 2009We’ll see how fossil fuels such as coal, oil, and natural gas are used to produce mechanical motion and how that mechanical motion is used to produce electric power. We’ll also examine solar and wind power generation Since the electric current extracts energy from the generator, something must do work on it to keep it turning.
When you turn a bicycle generator rapidly by hand, you can tell whether it’s part
of a completed circuit. If it isn’t part of a circuit, the generator turns relatively easily. If it is, the generator is hard to turn. Why?
we will talk also sbout Heating and Cooling the Steam , Solar Cells and Wind and Water Power
Electric Power Generation
Pure Sine Wave Inverter
Monday, March 23rd, 2009Pure Sine Wave Inverter
Block Diagram & Schematic
The inverter will converts 12 Volt dc from battery into 110 Volt ac, 50 Hz, sine
wave.the block dagram and schemnatic circuit of the inverter are shown in file Pulse train as shown in figures 5 is produced interchangeably from port (A)
and port (B) by microcontroller 89S2051 during the positive half and negative half of the sine wave. The pulse train is then inputted to the MOSFET power switching
circuit, which is next directed to the primary side of the transformer. Output of the secondary side is shown in Figure 6, which then be filtered resulting in the sine wave as seen in figure 7, where amplitude attenuation can reach up to 50%. Measured inverter output THD reaches 5-8%, where the largest harmonics appeared to be the second and third harmonics as shown in figure 8
Pure Sine Wave Inverter
Pure Sine Wave Inverter
Grounding in Apartment Building
Monday, March 23rd, 2009Q: The calculated load for an apartment building is 665 amperes, 120/240 volts. May the service-entrance conductors be two sets of parallel 350 Kcmil Type THWN copper conductors in separate raceways? I am using Table 310.15(B)(6) and doubling the ampacity of 350 Kcmil copper conductors to obtain an ampacity of 700?
A: The special or elevated ampacities of conductors permitted by Table 310.16(B)(6) stops at 400 amperes. It does not include elevated ampacities for service-entrance conductors in parallel.
The minimum size service-entrance conductors for a calculated load of 665 amperes is two sets of 400 Kcmil Type THWN copper or other copper insulated conductors with 75°C or 90°C insulation in two separate raceways. These conductors may be protected by a 700-ampere overcurrent protective device.
Grounding in Apartment Building
Embedded Robotics
Tuesday, March 17th, 2009Recently sensor networks research demonstrated the potential of networked embedded devices as a way to pervasively instrument the physical world. We argue that the same class of devices can be highly valuable to pursue unforeseen developments in the robotics area, especially in the networked and ubiquitous robotics subdomains. Our main contributions are a platform for Networked Embedded Robotics and its supporting software. We believe it to be the first publicly available design that is built from cheap commercial, non specialized hardware, while at the same time retaining compatibility with the majority of existing solutions like standard motes.
Embedded Robotics
Power Directional Relay
Tuesday, March 17th, 2009Phase distance relays are commonly applied on the low voltage side of a transformer to protect higher voltage lines The Compensator Distance Element Principle is a supe-
rior design for accurately applying distance relays through transformers. It is unaffected by common delta wye transformer connections and basically measures positive-sequence impedance Compensator Distance Elements can be affected by load,
causing the relay to over- or underreach Phase-pair distance relay designs can be applied, but relay reaches must be analyzed when reaching through transformer banks.
Power Directional RelayPower Directional Relay2
Harmonics in Electric Power Systems
Sunday, March 15th, 2009Harmonics cause
ß Transformers to overheat
ß Transformer secondary voltage distortion
ß Increased power system losses
ß Telephone and wired communication systems
noise
ß Neutral overloads
Other harmonic issues
ß Watt-hour meters
ß May read high or low
ß Protective relays
ß May not sense RMS values
ß Nuisance trip or fail to trip
ß Digital clocks
ß May run fast
Solutions
ß Use full sized or oversized neutral conductors
ß Oversize or harmonic rate transformers
ß Detune system (move capacitors, install reactors)
ß Filter (install passive or active harmonic filters
Harmonics in Electric Power Systems
Battery Chargers
Saturday, March 14th, 2009A battery charger is an electrical/electronic device that converts the incoming AC line voltage into a regulated DC voltage to meet the charging needs of the respective battery Although today’s industrial battery charging market is dominated by ferroresonant and SCR type chargers, new switchmode technologies are making headways into the industrial battery charger markets Battery charging is a complex electrochemical process, in which the discharged electric energy must be replenished from the electric network.
Download link
Shift Registers
Friday, March 13th, 2009Shift registers are a type of sequential logic circuit, mainly for storage of
digital data. They are a group of flip-flops connected in a chain so that
the output from one flip-flop becomes the input of the next flip-flop.
Most of the registers possess no characteristic internal sequence of states.
All flip-flop is driven by a common clock, and all are set or reset
simultaneously.
Shift Registers