Installation voltage transformers

Precautions to be observed while installing a voltage transformer 15/469... 

The TJ indicates that this apparatus cannot be used/installed on its own. The voltage transformer, as a component, has to be inserted in an enclosure complying with EN 50014 and 50019 increased safety, ensuring an appropriate tightness against the ingress of dust and water. The certificate is a component certificate... 

XI. 1.1 The tester should be placed on a level laboratory bench, allowing a 200 to 300 mm wide bench area in front of the tester. Ready access to the rear of the tester should be provided for routine maintenance and service requirements. Ensure that the vent on top or side of the JFTOT cabinet is not obstructed during installation or use. Adequate ventilation should be provided, and proper procedures for handling solvents and hydrocarbons should be used. A constant voltage transformer may be required by early versions of the instrument. Single-pha electrical power, 115 V-60 Hz-IS Amp or optional 220V-50 Hz-8 Amp with a ground outlet is required. 

Quality of power required for FMS systems is quite stringent in terms of frequency and voltage. Automatic voltage stabilizers, procured locally posed serious problems of frequent tripping etc. It look quite some time to resolve this problem by modifying these equipments installing isolation transformers and also ensuring stable power supply. 

Power Supplies and Controls. Induction heating furnace loads rarely can be connected directiy to the user s electric power distribution system. If the load is to operate at the supply frequency, a transformer is used to provide the proper load voltage as weU as isolation from the supply system. Adjustment of the load voltage can be achieved by means of a tapped transformer or by use of a solid-state switch. The low power factor of an induction load can be corrected by installing a capacitor bank in the primary or secondary circuit. 

For outdoor installations the recommended minimum creep distances for all types of voltage or current transformers are given in Table 15.1, according to lEC 60044-1 or lEC 60044-2. 

To prevent unacceptably high contact voltages [1,2], metal sheathing of power cables in transformer and switching stations and in the distribution network is connected to grounded installations, which have a low grounding resistance. This increases the danger of corrosion and makes corrosion protection more difficult if ... 

The potentials from larger grounding installations on the soil surface are essentially flatter but more extended than those from overhead power line pylons (e.g., power stations, transformers and switchboard plants). The maximum expected grounding voltage in case of failure and its variation at the soil surface can be obtained from the facility s management. 

The range and duty (i.e. off-load/on-load) can be specified to suit each particular installation. For standard distribution transformers of up to 3.15MVA rating for use purely as load supplies, off-load tap changing for a 5 per cent voltage range is normal. 

Where a.c. supplies exist, transformer-rectifiers are the most economical source of d.c. for cathodic protection systems. In the case of pipelines, standard transformer-rectifiers, either oil or air cooled, can be employed. They range in size from 5A, 5V for small systems to 100 A, 48 V for major pipeline schemes. A typical output for a well-coated cross-country pipeline in the UK would be 5 A, 48 V. In the case of sea-water jetties where the voltage required is usually low because of the lower sea-water resistivity, a typical rectifier size for a major installation would be 500 A, 18 V. For offshore pipelines and loading platforms where a fire hazard exists, it is usual to employ certified flameproof or intrinsically safe rectifiers to overcome any possibility of fire hazard should faults develop in the unit. 

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