THE CASH starved Punjab State Power Corporation limited’s (PSPCL) has mooted purchase of energy saving devices of questionable utility at a cost of Rs. 4 crore.
PSPCL in its 9th meeting had accorded administrative approval for purchase of 2 numbers Variable Frequency Drive (VFD) for unit 5 of Ropar Thermal plant on trial basis at a cost of Rs. 4 crore. The installation of costly energy saving devices is not likely to give the projected benefits.
VFD is an energy saving concept used for controlling the variables like flow/ head by speed control of induction motors through variation in frequency of input power. Memorandum approved by PSPCL, the copy of which is available with this scribe has claimed an energy saving of 20 percent is possible at unit 5 of Ropar Thermal plant.
The hypothetical calculations made in the memorandum shows 20 percent power saving with use of VFD. It has been further claimed that the complete cost of equipment would be recovered in 52.31 months.
At Ropar thermal plant the proposal for installation of VFD had been discussed and rejected a number of times during last five years. Even the present Director had made observations earlier on the proposal. According to official sources, at unit 5 the running load of ID fans is 134 ampere and its over load tripping is at 135 ampere. ID fans are already running near maximum possible load. This implies that there is no margin for adjustment so the usefulness of VFD is suspect.
A senior RTP engineer said that usefulness of VFD is in those cases where motors driving the equipment are partially loaded as in the case of Forced Draft Fans. The present system of controlling the draft through vanes is the best system under these circumstances.
At Lehra Mohabatt thermal plant second stage units has been provided with such devices. A senior engineer posted at Lehra Mohabatt plant said that VFD installed by BHEL are partially successful. A number of units tripping in the past have been attributed to VFD. The average running of VFD is less than 50 percent sources claimed. He further said that variable frequency device is useful energy saving device where the equipment is under loaded.
Under these circumstances the usefulness of VFD at Ropar thermal plant is debatable. The calculations have been made on the theoretical 100% availability basis and in practice the availability will be even less than at Lehra Mohabatt thermal plant as there is no margin on ID fans.
As per memorandum Ropar thermal plant is to arrange a loan of 90 percent of capital funds of 4 crore from Power Finance Corporation or Rural Electrification Corporation after hypothecation of future assets. The balance 10 percent shall be arranged by PSPCL. The necessity to install VFD at unit 5 on trial basis after taking a loan of around 3.6 crore cannot be justified, said another official.
The process of purchase case already received against earlier tenders has been started with the opening of price bid of three firms on January 25.
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