IEEE C57.12.52-2012 pdf free

IEEE C57.12.52-2012 pdf free.IEEE Standard for Sealed Dry-Type Power Transformers, 501 kVA and Higher, Three-Phase, with High-Voltage 601 to 34500 Volts, Low-Voltage 208Y/120 to 4160 Volts-General Requirements.
The low-voltage neutral shall be a bushing insulated br the appropnae low-frequency voltage insulation level shown in IEEE StdC5l.l2.0I.
When a grounded-Y winding is involved, the connection from he neutral terminal to ground shall be furnished by the manufacturer as part of the associated equipment such as switchgear or terminal compartments.
6.5 Tap changer
Taps may be accomplished by internal links, a terminal board or a tap changer. If a tap changer for deenergized operation is supplied, it shall be provided with the operating handle brought out through the cover, or through the sidewall in segment I, at a height convenient for the design.
The tap changer handle shall have provision for padlocking and shall provide visible indication of the tap position without unlocking. A 9.5 mm (3/8 in) minimum diameter hole shall be provided for the padlock.
The tap changer position indicating plate shall be marked with letters or Arabic numerals in sequence. The letter ‘A” or the Arabic numeral “1 shall be assigned to the voltage rating providing the maximum ratio of transformation.
NOTE—The ratio of transformation is the rated voltage of the high-voltage winding divided by the rated voltage of the low-voltage winding.
6.6 Temperature Indication
6.6.1 Top gas temperature indicator
A top gas temperature indicator shall be provided. Top gas temperature indicators may be either dial-t>pe or electronic, Unless specified otherwise, it shall be mounted near the top of the tank in segment I. The probe for the gas temperature monitoring should be located no higher than 300 mm (approximately 12 in). above the top of the core and coil to more closely monitor the gas temperature near the coil insulation, If the gauge is elevated more than 244 cm (96 in) above the outside mounting surface of the tank, the gauge should be tilted downward for easier viewing.
If a dial-type thermometer is supplied, it shall be direct-stem-mounted in a closed well as high as possible. but no higher than X ft. If the mounting is higher than 8 ft. the gauge must be tilted downward. For dimensions of the well, see Figure 3. The thermometer shall have a dark face dial with light markings. a light-colored indicating hand, a contrasting color maximum indicating hand, and provision for resetting. The diameter of the dial (inside bezel) shall be 114 mm (4-1/2 in) ± 25.4 mm (I in). The dial markings shall cover the range from 0 °C to 220 °C.IEEE C57.12.52 pdf free download.