Just how global is Jim Henson Productions?

The creators of such memorable characters as Miss Piggy and Kermit the Frog are so global that, while the company is headquartered here, it has never produced a program in the United States.

Since Great Britain's Lord Lew Grade provided the financial backing for Henson's "The Muppet Show" series in the mid-1970s via his Associated Television Company, Henson has sought out alliances around the world.

Those partnerships have included a linkup with the CBC on the show "Fraggle Rock"; its current high-definition television production experiment with Japan's NHK network; plus a wide array of programing co-ventures with British TV companies.

Among the programs currently in the works at Henson Productions is a series co-produced with the British independent TV company Tyne Tees Television, "The Ghost of Ffafner Hall," a musical/educational series with a new cast of Muppet characters and high-profile guests, including Bobby McFerrin and Joni Mitchell.

"Ffafner" is set to debut in the United States on HBO and in other countries this fall.

Henson Productions is tackling not only its first hour-long series, but also its first prime-time series, "The Jim Henson Show," currently in production in Toronto for a spring debut on NBC.

While declining to share any on-the-set anecdotes, Bob Beitcher, managing director of Jim Henson Productions, says with a laugh, "I think we probably underestimated what it takes to mount 13 hours of prime-time production."

The series will be an amalgamation of Henson Productions past and president, with Mr. Henson making his first regular on-screen appearances in one of his series.

The show ill also feature such old favorites as Kermit the Frog in "very electronic" Muppet variety-show segments, plus episodes from Henson's "The Storyteller," a series produced with Britain's Television South that has yet to air in the United States.

Some episodes will take on an identity all their own, such as "Dog City," described by Mr. Beitcher as a 1940s film noir production with an all-dog Muppet cast.

Mr. Beitcher says there is an "implicit" global attitude at the company because Mr. Henson strives to create programing that's "beneficial to all people, programing of togetherness and peace."

While noting that the family/children's television niche that Henson Productions has carved out is particularly suited to attracting global interest, Nigel Pickard, controller of children's programing at Television South, says he believes the company has become successful because "Henson has a formula based on not only excellent visual elements and excellent characters, but excellent plots.

"The really marvelous thing about Henson is that they create everything from scratch, with a blank piece of paper, and it appeals to an international audience every time," he says.

That appeal manifested itself most recently a few weeks ago, when "Fraggle Rock" premiered in the Soviet Union.

Russian viewers were so taken with the underground Fraggle characters and the world they inhabit that Gosteleradio received 3,000 "Fraggle" fan letters within days.

"That's completely unheard of for them," said Mr. Beitcher. "They want to buy more shows and air it on a regular basis."

"Fraggle" is an especially global production because segments featuring the bumbling human character Doc and his dog, Sprocket, were recast and taped three times, for French, German and English audiences.

That method of handling the series to boost its international appeal closely resembles similar global co-productions of "Sesame Street," the Children's Television Workshop series that Mr. Henson co-created.

All told, "Fraggle" has been seen in more than 90 countries and dubbed in 14 languages.

Co-productions have paid off in terms of quality as well as audience appeal, according to Peter Orton, chief operating officer of Henson Productions' distribution unit, Henson International Television, and a Children's Television Workshop alumni.

"The interesting thing about co-production is that for those American companies just beginning to do them, it's a great way to cover the deficit," he says. "But coming up with a network concept and then trying to set a U.K. partner to cover the deficit is not the way we do it."

Instead, Henson Productions makes programs of equal appeal to both partners, he says.

Adds Mr. Beitcher, "It's probably just as expensive to sheet in England as the U.S., or even more expensive. But you get more money on the screen (through co-productions) than if you just found someone over here in the U.S. to buy it."

Henson Productions' efforts toward co-production had a major breakthrough about four years ago when the company purchased international distribution rights to "The Muppet Show" from ITC Entertainment, which was then owned by Lord Grade.

And it has expanded its distribution efforts over the years to include not only Henson-created productions, but top-quality family programing from other international producers as well.

In addition to "Ffafner" and "Henson Hour," the company recently completed production with Television South West, a Plymouth, England-based ITV company, on "Jim Henson's Mother Goose Stories,"

It's also working on "The Witches," a feature film adaptation of Roald Dahl's story. The film, which is mainly live action, features Angelica Huston and is due out in August from Warner Bros.

Mr. Beitcher says those efforts, as well as plans for new productions, could make 1989 the company's busiest year yet.

Currently on the drawing board is a series patterned after "The Storyteller," which centers on old European folk tales. The new series project would retell Greek myths in television form.

Henson Productions is also developing a series "dealing with the environment which will be international in scope," one of several ventures the company is working on with Japan's NHK.

Henson productions plans to further expand into prime-time television with a half-hour situation comedy "that has a fantasy element, a creature or a group of creatures," Mr. Beitcher says.

In addition to Henson International Television and production groups in both London and New York, the company's endeavors include the Creature Workshop in London, which makes puppet characters for Henson Productions as well as others.

It also has publishing and licensing units, plus Muppet Meeting Film, which creates business film segments for the corporate world.