The Senate approved Wednesday a one-year extension of a moratorium designed to prevent the collapse of the federal insurance fund that backs the nation's thrift industry.

On a voice vote, the Senate agreed to extend the restrictions banning healthy savings and loan institutions from converting their charters to that of banks, thereby shifting their insurance premiums from the strained Federal Savings and Loan Insurance Corp. to the more stable Federal Deposit Insurance Corp.The existing moratorium expires Aug. 10, and several thrifts have already indicated their intention to alter their charters.