LARGE CURRENT RECTIFIERS : PRODUCTS

Rectifier Application
22KA 950 Forced Air Cooled Rectifier

       Industrial applications of large current rectifiers:

	Factory general DC supplies
	DC supplies to industrial Machines & processes
	Electroplating
	E. S. P. Rectifier for use in pollution control of thermal Power Plant
	Aluminium smelting
	Caustic Soda plant
	Graphite furnace
	Battery Charger
	DC supplies for cranes
	Potassium chlorate production
	Mangense dio-oxide plant
	Hydrogen Production
	Thyristorized L.V. Rectifiers for water upgradation of Nuclear Power Plant.

Ratings

Rectifier equipment can be supplied from the smallest size upwards with any combination of output current and voltage. They are available for light or heavy industrial service with overloads in accordance with IEC 146-1973

Typical overload class II – 150% for 60 secs once in 24 hours.

Equipment can be designed to suit any special duty cycles or over loads upon request.

Cooling

Transformer

Oil Natural (ON)
Oil Natural Air Forced (ONAF)
Oil Forced Air Forced (OFAF)
Oil Forced Water Forced (OFWF)

Rectifier

Natural
Forced Air
Forced air with air to water heat exchanger
DM water forced with AM water to raw water heat exchanger.

Basic Connection

The choice of connections depends partly upon the DC voltage required, however it is determined by a combination of efficiency and cost considerations.

3 Phase bridge (6 pulse) The double way connection gives a 6 phase rectification with a 120 degree conduction angle. This is most commonly used for industrial power supplies.

Double Star (6 pulse) with this connection the 6 phase secondary windings are separated in two opposed star groups, the neutral points of which are connected through an interphase transformer. The voltage equalising effect of the IPT enables the two star group to share the current & 120 degree conduction occurs

12 Pulse circuits : For 12 pulse working two 6pulse rectifier circuits, two equipment or two groups of equipment to be phase by 30 degree from each other. This is usually achieved by having star-delta primaries. On very large installations, pulse numbers greater than 12 can be obtained by suitable phase shifted a no. of 6 or 12 pulse rectifier.

Protection

The rectifier and transformer are protected against over current surge voltage and excess temperatures, etc. and are designed so that internal component failure cannot cause damage. Additional protective circuitry can be provided when specified.

For Rectifier

	Cooling Failure
	Air /Water temperature
	Supply failure
	Over Current/Short circuit
	Over Voltage
	Diode failure

For Transformer

	Buchholz gas and surge
	Over Current
	Oil temperature high & excess
	Winding temperature high & excess