How Computer Power Supply Voltages Are Generated

A computer power supply unit (PSU) converts AC mains voltage (typically 220V or 110V) into several DC voltages required for different components of a computer. 

What is ATX?

ATX (Advanced Technology eXtended) is a standard developed by Intel in 1995 for motherboards, computer cases, and power supplies. It defines the size, connector placement, and cooling system requirements for PC components.

What are thermocouple meters?

Thermocouple meters convert applied current (a-c or d-c) by thermoelectric effects into deflection currents which register on a PM moving-coil couple actuated by heat generated at the junction formed by two strips of dissimilar metal. One strip carries the heat-generating input currents, the other carries heat-produced currents to the meter movement.

Thermocouple meters are used to measure a wide range of either a-c or d-c currents and give an accurate picture of the effective, or heats producting, value of a current no matter what its nature. The meters are relatively expensive and the thermal delay in converting input electricity to heat makes them sluggish.

Lighting on ships. General Requirements

In all rooms, spaces and locations of the ship where lighting is ne cessary to ensure the safety of navigation, operating of machinery and equipment, as well as accommodating and evacuation of passengers and crew, stationary fixtures of main lighting are to be installed.

Lighting fixtures installed in rooms and spaces, where mechanical damage is possible to the glass hoods are to be provided with' protect ing gratings.

AC Indicating Meters

The moving iron-vane type is the most common a-c meter. In it induced eddy currents are used to produce magnetic force on a structure bearing a pivoted pointer and a thin iron element called a vane. The vane has no coil. 

The stationary magnetic field is produced by a single current-carrying coil surrounding both the fixed metal element and the pointer movement. This coil is so arranged that its own field induces a field in the moving vane and in addition generates attractive or repulsive magnetic forces with respect to its own self-produced magnetic field. Deflection is basically proportional to the current through the main coil.

Indicating DC Meters

Fundamentally, all meters measure current and in this sense are ammeters. When they have low internal resistance so as to produce no effect on a circuit's performance and are actuated through direct connection in series with the main current path, they are truly ammeters.

When they have high resistance so that they may be placed in shunt or directly across a voltage source they are called voltmeters. Their indication of voltage is based on the product of a known, calibrated internal resistance in series with the meter movement, and the current flowing through that resistance.

Superconducting DC Motors for Marine Propulsion

Electric propulsion power transmission is usually economical only for special vessels. However, superconducting motors with their greatly reduced weights and sizes indicate that this type of propulsion may become more widespread in the future.

The energy crisis of the early 1970s provided impetus for more sufficient energy conservation and for exploiting hitherto untapped resources.

The superconducting dc motor adds a potent new factor to this situation. It offers the best of these options in that it is lighter than the equivalent conventional ac motor and is a dc motor which may be operated from an ac generator via a simple diode-rectifier-convertor. It offers all the advantages of a dc propulsion system, together with high efficiency, and performance characteristics particularly suited to high efficiency propellers; with no practical power limit.

What are Thyristor Convertors?

The convertors in dc drive systems are designed to control and supply separately-excited dc machines in applications that demand rapid response, high accuracy and great reliability.

The convertors are available with single-convertor arrangement and in double-convertor arrangement.

Operation. The armature supply unit has a closed-loop current control system which ensures that the armature current follows the set current, reference. The system is based on a current controller, the output signal of which can influence the armature current via the control pulse circuits and the thyristor unit.

What is a DC Voltage Transducer?

DC Voltage Transducer delivers an output voltage proportional to the armature voltage or induced voltage. The output signal is mathematically isolated from the input voltage. The armature current signal is used to compensate the output signal for armature current variations in such a way that the output signal is approximately proportional to the induced EMF.

Where accurate EMF measurement is required, the measuring circuit also has an input which may be connected to the terminal of the machine. The voltage drop across the commutation winding of the machine is then used for IR compensation, and this arrangement therefore compensates to a considerable degree for the dependence of winding resistance on temperature.

What are convertors?

Presentation. The convertors in dc drive systems are designed to control and supply separately-excited dc machines in applications that demand rapid response, high accuracy and great reliability.

The convertors are available with single-convertor arrangement and in double-convertor arrangement.

Electric Drives of Towing Winches

Flexible-link towing is a physical process involving unsteady motion of inertia masses interconnected by a flexible element. Reliability of towing depends on selection of an optimum length of the towline and on minimizing the towline, overloads under various conditions. Non-automatic towing winches with a pull of 120 kN and above may be used with three-speed a-c cage motors controlled by means of magnetic controllers.

Taking account of the optimum speed ratio of the winches for towlines 37.5 to 48.5 mm in diameter use may be made of three-speed motors with a speed ratio of 1:2:4, developing a rated power and a rated pull at the medium speed; the motors are controllers.

What is the electronic control of motors?

It is necessary to control motors. That is, motors must be started, stopped, and reversed, and, within limits, it must be possible to control their speed.

The controls needed to perform these various functions on DC motors are designed to alter the quantity or the direction; of the current in the field or in the armature of the motor. On DC controls, these functions were shown to consist mainly of resistances, switches, and solenoids.