A massive shortfall in power generation in some of the northern plants saw the Indian capital witnessing power cuts lasting several hours Tuesday.

With private distribution companies, or discoms, offering no reasons for making people sweat it out in the humid weather, consumers were put to a lot of discomfort.

"The situation is expected to last for another day or two till the power supply in the northern region improves," S.R. Sethi, director (operations) of the state transmission utility Transco, told.

"We are facing a shortfall of 600-700 MW power supplies from the national grid with some power plants in Himachal Pradesh and those of National Thermal Power Corp (NTPC) not fully operational. We are resorting to power cuts of 100-250 MW and above in different areas to make up for the shortfall," Sethi said.

Private power distributor BSES said it was a "planned shutdown", but failed to give reasons why consumers were not adequately warned.

Said Rajani Mukherjee, an insurance company employee: "We were in hell the whole day. Nothing was functional, no air-conditioners, not even the coffee machine. What is going on?"

Due to heavy rains leading to silting in its catchment area, the Nathpa Jakhri power plant in Himachal Pradesh is operating only at one-third its capacity of 1,500 MW. The Himachal Pradesh-based Baspa power plant's operations were also affected.

Some of NTPC's power plants like Rihand and Singrauli too are not operating at full capacity due to coal shortage and other problems. Some of these plants are expected to take a week to return to full capacity generation, experts said.

In addition, full supplies from the Rajasthan Atomic Power Plant are not being received, according to the Power Grid Corp of India Ltd (PGCIL), which looks after the national grid.

"Altogether there is a shortage of 4,950 MW shortage in supplies in the northern region. Part of this shortage is being bridged with both western and eastern regions supplying us 500 MW each," an official of the PGCIL said.

In the case of Delhi, PGCIL estimates a supply shortage of about 300 MW as against a normal load of 3,150 MW-3,350 MW.

The current demand in the capital is about 3,160 MW. Growing at nearly five percent annually, Delhi produces only about 1,400-1,500 MW power.

For the rest, it is dependent on the northern grid, which is currently facing a 4,950 MW shortfall.

To cope with this, PGCIL has been resorting to about 2,500 MW load shedding in the northern area while importing about 1,000 MW from the western and eastern region.

The power situation is likely to gradually improve once the Nathpa Jakhri or Sutlej power plant becomes fully operational with Delhi being entitled to about one-fifth of the total capacity of 1,500 MW, Sethi said.