Reduced voltage systems

Reduced voltage systems (110 volts) are particularly suitable for portable electrical equipment in construction work and in high conducting locations such as boilers, tunnels and tanks where the risk to equipment and trailing cables is high and where the body may be damp. 

Reduced voltage systems (110 volts) are particularly suitable for portable electrical... 

Reduced low voltage systems When the working conditions are relatively severe either due to wet conditions or heavy and frequent usage of equipment, reduced voltage systems should be used. 

Is the supply voltage for tools and equipment the lowest necessary for the job (could battery operated tools and reduced voltage systems, e.g. 110 V, or even lower in wet conditions, be used) ... 

Reduced-Voltage Starting Reduced-voltage starting is used to reduce system voltage dip. Voltage dips must be limited otherwise, they may drop other motors off the line, cause synchronous motors on the system to pull out of step, or cause objectionable lamp flicker. 

The voltage drop during starting should be calculated using the speed current data, locked rotor power factor, and the distribution system con stants. Speed-torque values at this reduced voltage can be calculated, assuming that the torque varies as the voltage squared. These values are compared to driven equipment curves. 

Studies showed that a BESS on the MP L system could (i) help stabilize and improve the power quality of the system, i.e., reduce voltage and frequency deviations (ii) reduce reliance on the diesel generator, and thus realize attendant savings in fuel-related costs. Subsequently, the GE-GNB alliance (see Section 10.5.8) provided a suitable, 1.6-MVA (10s)/1.0-MW (continuous) BESS, which was interconnected at a 12.47-kV sub-station. Construction began in April 1996, was completed in December 1996, and the BESS has been operational since February... 

Supply system voltage disturbances (e.g., loss of supply, reduced voltages, re-coimec-tion of supply)... 

A hot runner system is required for conserving material and reducing the amount of rework required. Externally heated hot runner systems are always preferable to the internally heated systems as the externally heated hot runner systems maintain uniform flow of melted material with a constant melt temperature over the cross-section of the hot runner. The heat energy can be evenly distributed from outside to inside in the melt. Low voltage systems (5 or 24V) have been observed to function well. 

This type of system is becoming less common as a result of the increasing use of reduced voltage (llOV centre-tapped-to-earth) and even battery-operated Class II hand tools in construction sites and other harsh environments. It does, however, have a role in ensuring the integrity of earthing systems where there are high levels of protective conductor current (see BS 7671, section 607). 

Chapter 4, on construction sites, provides a comprehensive explanation of reduced low voltage systems and, at Table 4A, gives recommendations on the frequency of inspections and tests for installations and equipment used on construction sites. 

Elecric shock as a result of direct contact, means that a person makes contact with part of the circuit which is intended to be live. The only form of protection against direct contact is to prevent such contact in the first place. This can be achieved by following the same principles of risk assessment and machinery safeguarding discussed earlier, namely to provide fixed guards, enclosures or insulation. However, if access is foreseeable, then permit-to-work systems should be operated. It should be remembered that intrinsic safety is an absolute priority in removing the risk of shock injury. This can be achieved by reducing the system voltage in areas of likely contact to such an extent that it cannot result in an electric shock. 

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