The Senate voted 87 to 1 last night to approve a Civil Service reform measure that President Carter and a bipartisan group of senators say is the most sweeping since the federal civil service system's birth in 1883.

The bill was adopted after six hours of debate, during which the Senate passed several amendments amied at strengthening safeguards against politicizing the federal bureaucracy.

Senate Majority Leader Robert C. Byrd (D-W. Va.) said the reform measure is "without a doubt . . . truly landmark legislation." He said the bill will greatly enhance the chance for an "efficient and effective government" where a worker's performance on the job is more important than his political leanings.

The House is considering a sharply different version of President Carter's civil service reform proposals and eventually the House and Senate measures will go to a conference committee.

Among other provisions, the Senate-passed version would create a Senior Executive Service composed of about 9,000 federal managers, with 10 percent of them political appointees! They would be able to rade some of their current job security in exchange for higher pay and other rewards for superior performance, but they would risk dismissal or demotion for poor work.

In addition, about 72,500 mid-level managers and supervisors - workers with GS-13 to GS-15 job rankings - no longer would be guaranteed periodic pay raises. Any pay boosts would be related to their performance. Moreover, all federal workers would have what the administration says would be "quicker and clearer" appeals if they are fired.

Under the reorganization, the Civil Serive Commission would be split into two bodies. An Office of Personnel Management would represent the interests of managers and be under the wing of the White House. A Merit Systems Protection Board would protect employes against any management abuses. Both of those boards currently are under one roof.

The lone dissenter in yesterday's vote was Sen. William I. Scott (R-Va.). Sens. Paul S. Sarbanes (D-Md.), Charles McC. Mathias Jr. (R-Md.) and Harry F. Byrd Jr. (I-Va.) voted for the measure.

Among other provisions approved yesterday by the Senate were:

One that would permit government "whistleblowers" to voice allegations about wrongdoing in their agencies to a special government lawyer who would be prohibited from disclosing the name of the person making the charges. That lawyer could order the offending agency to undertake an investigation if it seemed likely the allegations were true.

A limit of $47.500 on the amount that retired military personnel could earn from their combined military pensions and federal salaries. No such limits are in effect now, and 200 military retirees working in the federal government - often called "double dippers" - now earn between $60,000 and $80,000 annually from their pensions and salaries.

A measure that would give the Merit Systems Protection Board the right to overturn work policies adopted by the presidentially appointed director of another new body, the Office of Personnel Management. This provision is designed to curb a president's possible attempt to use the bureaucracy's 2.9 million workers for political purposes.

As a handful of senators debated the complex provisions of the reforms. Civil Service Commission Chairman Alan Campbell was in Vice President Mondale's office off the Senate floor trying to ensure that no provisions unacceptable to the Carter administration were included.

As the debate extended throughout the afternoon, Campbell said he was not entirely happy with the adopted provisions, but said "they do not undermine the intent of the bill."

He specifically said he was not pleased with the authority the Senate granted to the Merit Systems Protection Board to overrule policies approved by the Office of Personnel Management.

Nonetheless, Campbell said the legislation was "moving along very well" and that the Senate version is "much more preferable" than a version now awaiting floor action in the House.

The Senate version incorporates Carter's proposals almost entirely. The exception is that the Senate bill does not limit the federal job hiring preference for veterans as Carter had requested.

However, the Senate did adopt a provision yesterday that would eliminate job preference for retired military officers.

The administration's objection to the version passed by the House Post Office and Civil Service Committee is that it would stengthen too much the bargaining rights of federal worker unions.

Campbell and other Carter administration officials have been negotiating with some House members over the bill but have not reached an agreement. The House committee version is scheduled for debate on the House floor Sept. 7.

"We're either going to work something our or fight it out on the floor," Campbell said.

The most spirited debate on the Senate provisions yesterday centered on whether to curb the combined salary and pension of military retirees who work in the federal government. The proposal, sponsored by Sen. H. John Heinz III (R-Pa.), will not affect current retirees working in the government.

Heinz described the provision as an "extremely modest" start at dealing with the problem of "double-dipping."

But Sen. Barry M. Goldwater (R-Ariz), a retired Air Force Reserve general, objected strenuously to the measure. "I'm getting a little sick and tired of the former military men being kicked around," Goldwater said.