It also affirmed its preliminary 'BBB-' long-term issue rating on the company's proposed issuance of Indian rupee-denominated senior secured notes.
"The rating on ATL reflects our expectations of stable cash flows driven by a favourable regulatory environment, the company's power transmission business and its good operating record," S&P Global Ratings credit analyst Mehul Sukkawala said in the statement.
However, the company is dependent on two key assets, exposed to somewhat weak counterparties and has a short track record of operations.
An obligation rated 'BBB' exhibits adequate protection parameters. However, adverse economic conditions or changing circumstances are more likely to lead to a weakened capacity of the obliger to meet its financial commitment on the obligation.
"We believe ATL benefits from a predictable tariff-setting mechanism, which results in stable cash flows. Tariff recovery is linked to network availability and is independent of volumes, protecting ATL from volume risk. It allows the company to recover its fixed costs and earn assured return on equity," the statement said.