The company said this was because power was having to be diverted from high-voltage lines to less powerful lines and that emergency shutdowns would be needed if consumption rose sharply.
"Terrorists are trying to destroy our substations because they want to deprive as many people as possible of electricity at once," the company said in a Facebook post.
As Russia continues shelling, targeting mainly energy and water supplies, the company reported another attack on Saturday though it did not say exactly where.
