delphia Communications, the cable television operator, and more than 200 of its subsidiaries filed for bankruptcy protection yesterday in Manhattan after a month of struggling to find an alternative.

The company, which has been under investigation by the Securities and Exchange Commission and two federal grand juries, said that it would continue to provide cable service to more than 3,500 towns and cities and that employees would continue to be paid.

Adelphia said it had arranged a loan of $1.5 billion to help it reorganize. The lead banks on the loan, it said, were J. P. Morgan Chase and Citigroup. A court hearing to approve a part of the loan is set for Friday, the company said last night.

"Entering into these proceedings will enable us to fully evaluate our enterprise without the immediate pressure to sell valuable assets," the company's chairman and interim chief executive, Erland E. Kailbourne, said.

Adelphia's troubles began in March when it disclosed that it had guaranteed loans of $2.3 billion to the Rigas family, the company's controlling shareholders. Since then the size of the loans disclosed has grown to $3.1 billion, and several other transactions between the company and the Rigas family have come to light.

The company, which is based in Coudersport, Pa., will be reorganizing under a fractured board and faces the likelihood of lawsuits from shareholders and bondholders.

Even under bankruptcy protection, the company's future as the nation's sixth-largest cable operator is uncertain. There are strings attached to the $1.5 billion in financing that prevent Adelphia from using all the money unless certain goals are met, including the filing of an accurate annual report.

Bondholders have said they will fight to block an eventual sale of the company's assets.