Bobby Carpenter of the Washington Capitals has felt somewhat deprived because he never represented the United States in the Olympic Games. So the third Canada Cup series, which gets under way tonight, will serve as Carpenter's Olympics.

Carpenter, 21, was a junior at St. John's High School in Peabody, Mass., when the U.S. team won the hockey gold medal in the 1980 Winter Olympics. One year later, he became a member of the Capitals, making him ineligible to participate in this year's Olympics.

"It would have been great to play in the Olympics," said Carpenter, one of four Capitals on Team USA, along with Rod Langway, Bryan Erickson and 1980 Olympian Dave Christian. "But three years was too long a time for me to wait. This series is like the Olympics -- a professional Olympics."

Carpenter sat out Team USA's final exhibition game, a 9-7 victory over Sweden Monday in Minnesota, because he broke two ribs in an exhibition last week against Canada. He said he will be in uniform tonight, however, wearing a protective flak jacket, as the United States opens the six-nation tournament against Sweden in Halifax, Nova Scotia.

In other openers, Canada will play West Germany, considered the weakest team in the tournament, in Montreal tonight. The Soviet Union, the 1984 Olympic champion, will meet Czechoslovakia Sunday in Montreal.

The six teams play a round robin, with the four teams compiling the best records advancing to the semifinals. The winners of the semifinal games will meet in a best-of-three series for the championship.

In 1976, Canada won the round robin with a 4-1 record and defeated Czechoslovakia in two straight for the championship. Canada also had the best record (4-0-1) in the 1981 round robin, but lost to the Soviets, 8-1, in a one-game final.

The Capitals have three other players in the series. Right wing Mike Gartner is playing for Canada, and Bengt Gustafsson and Peter Andersson are playing for Sweden.

Much of the U.S. hopes rest with Buffalo's Tom Barrasso, who came directly out of high school last year to win the Vezina Trophy as the NHL's top goaltender.

Team USA, which has a combined 3-6-1 record in two previous Canada Cups, is relatively weak at forward, where the Soviets and Czechoslovakians excel. Most of Coach Bob Johnson's offensive talent was at center, so he moved several centermen to the wings, including Carpenter, Christian and Mark Johnson.

Team USA has been bolstered on offense by the addition of Bryan Trottier of the New York Islanders. Considered one of the best two-way players in the NHL, Trottier, who is from Val Marie, Saskatchewan, qualifies to play for the United States as a dual citizen because he is a North American Indian.

The U.S. team has one key injury. Pat LaFontaine of the New York Islanders missed part of Team USA's 2-2-1 exhibition schedule with a knee strain, and will sit out at least the game against Sweden, according to Bob Johnson.

Canada Coach Glen Sather created some controversy by inviting eight of his Stanley Cup champion Edmonton Oilers to camp and keeping them all on the 22-player roster. Gartner said the move may have been the right one since the Canadians had only three weeks to practice together.

"In past years, they (coaches of Canadian teams in Canada Cup and world championship tournaments) just put a team of all-stars out there -- the five best players they could," said Gartner. "This time, we are putting out five players at a time who play the best together."

The Canadians have offensive power in Edmonton's Wayne Gretzky, who was accused of dirty play and spearing by Soviet Coach Viktor Tikhonov after the USSR's 5-4 exhibition victory Wednesday. He probably will be teamed with regular linemate Mark Messier.

The player who may have the most impact on the series is one who will not be there.

Vladislav Tretiak, 32, tended the Soviet goal in most key games over the past 12 years, but announced his retirement after the February Olympics. His replacement, Vladimir Myshkin, is solid, but does not compare to Tretiak.

Sergei Yashin scored twice against Canada Wednesday, and was the victim named in Gretzky's alleged spearing incident.

The Czechoslovakians, who lost to the Soviets, 2-0, in this year's Olympic gold medal game, could be a factor in the tournament. They have winger Jiri Dudacek, who was listed by the NHL's Central Scouting Bureau as "the best player available" in the 1981 draft.

Sweden, once a respected team in international play, could end up an embarrassment. Borje Salming, Stefan Persson, Anders Hedberg and Anders Kallur are among a number of top-notch NHL players who declined to play for Sweden in the series.

West Germany, in the Canada Cup for the first time, is there solely to fill out the field. Its top player is 6-foot-7 Erich Kuhnhackl, a 34-year-old center.