STAMFORD, Conn., Oct. 27— Back in 1932, in the depths of the Depression, the General Electric Company found it tough to sell refrigerators. Consumers, hard pressed to buy even food to fill a refrigerator, were hardly interested in purchasing new appliances.

But General Electric solved this by setting up a credit subsidiary, the General Electric Credit Corporation, to provide consumer financing and get appliance sales rolling.

In the nearly five decades since, G.E. Credit has grown to become one of the invisible giants of finance. It owns the nation's largest fleet of tankers (by tonnage), is the biggest industrial equipment lessor, offers residential second mortgages and finances such new ventures as Atari Inc.'s ''Pong'' games.

G.E. Credit is part of the new breed of financial hybrids to emerge as the lines between traditional financial institutions continue to blur. The nation's sixth-largest finance company behind such concerns as the General Motors Acceptance Corporation and Ford Motor Credit, G.E. Credit's success has drawn the wrath of commercial bankers who compete against it but face Government regulations that G.E. Credit does not. 'Tremendous Advantages'

''G.E. has tremendous advantages over the banks,'' said Fred Hammer, an executive vice president at Chase Manhattan Bank. ''We can compete with anybody if we are allowed to do so. But there are questions as to the kinds of services we're able to provide. There's only a limited list of services we can participate in.''

Unfair is the word frequently used by commercial bankers, who assert that they are hampered by Government regulations that limit their ability to make money.

Bankers point to restrictions on interstate banking that prohibit them from obtaining deposits across the nation; to Federal Reserve rules that require them to keep money in interest-free Government accounts, and to limitations on entering such fields as insurance, where the customer payments provide a core of funds that can be reinvested at higher rates.

In response, G.E. Credit asserts that banks have historically benefited from a lower cost of money because of their low-interest, passbook savings deposits. And the banks still benefit, G.E. says, from huge borrowing capacity -largely because of Government insurance on deposits - that enables them to maintain a larger loan portfolio.

This larger borrowing capacity, or leverage, also enables banks to operate on a smaller profit margin for the same return on its equity as G.E. Credit. G.E. Credit maintains a 7-to-1 ratio of debt to equity, compared with banks, where a 20-to-1 ratio is not uncommon. 'Unfair Competitive Advantage'

''Banks operate with outrageous leverage,'' said John W. Stanger, president and chief executive of G.E. Credit, in an interview in his office. ''We have to operate without the lender of last resort and at substantially lower leverage. Banks choose to ignore that unfair competitive advantage versus commercial and industrial finance companies.''

But behind this debate is the recognition that G.E. Credit has grown to a point where it is a tough competitor for commercial banks. As recently as three to four years ago, that was not the case.

''They are a very aggressive, very formidable competitor,'' Mr. Hammer said. Added Arthur J. Garland, a vice president of Dean Witter Reynolds Inc., ''They happen to be a very savvy group, and savvy people happen to win their share of deals.''

G.E. Credit, with assets of $9.3 billion, has traditionally specialized in commercial secured lending, touching credit risks that commercial banks, until now, had shunned. For instance, it might finance the inventory of a small brass manufacturer whose balance sheet is too weak to get a line of credit from a bank, or it might devise a lease-purchase agreement for a construction equipment distributor to buy a fleet of trucks. These deals, which generally provide higher margins, require a clear idea of the value of the loan collateral.

G.E. Credit's adherence to secured lending - loans secured by a physical asset or an income stream rather than by the general credit of the borrower - was one of necessity. Because of its lower leverage, the company was forced to specialize in lending that provided higher margins in order to maintain a healthy return. 300 Branches Nationwide

As a result, G.E. Credit developed a network of 300 branches across the nation, staffed with specialists in such fields as trucking, mining and other basic industrial companies, who have the freedom to structure loans, so long as they are profitable. More recently, banks, suffering from the gradual loss of cheaper deposits, have begun to move into this field.

''I can't think of a loan that G.E. wouldn't do,'' said Noel T.G. Delaney, a research analyst with L.F. Rothschild, Unterberg, Towbin. ''G.E. Credit will lend against anything as long as the deal makes economic sense. They won't let tradition get in their way.''

In recent years, G.E. Credit has moved away from consumer lending, because of state interest rate ceilings and high loan losses. Starting in the mid-1960's, it moved into leveraged leasing, a complicated form of financing that offers low-cost financing to the equipment user but which provides tax shelter for the parent corporation, G.E.

Lately, G.E. Credit has done more with real estate loans, second mortgages, commercial real estate financing and mortgage insurance. The finance concern also owns a life insurance company but, to date, its contribution to net earnings has been modest.

Illustrations: 3 graphs of G.E.'s portfolio