下記によりますとThe terms "fail-open" and "fail-close" are frequently used to mean the opposite of each other.だそうですので、"RTA circuit breaker fails colsed (故障時閉)"は"RTA circuit breaker fails open (故障時開)"の誤記である可能性があると考えます:

"fail-safe (fail-open,ﾊfail-close)"
Definition: fail-safe (fail-open, fail-close): A philosophic point of view. When a system fails, how should it leave things: secure or unsecure? For example, if a firewall crashes, should it disable all network connectivity, or should it allow network connectivity to continue unprotected? A lot of security vulnerabilities occur because designers make the wrong choice. It is often easier to cause a system to fail than to break through it, so security items should probably fail in such a way to result in greater security at the expense of stopping everything. Confusion: The terms "fail-open" and "fail-close" are frequently used to mean the opposite of each other. Some people think of a door, which when "open" allows things to pass through. Other people think of an electrical circuit, when "open" stops the flow of current (and conversely, a "closed" circuit passes current). Therefore, use the word "fail-safe" instead in order to avoid confusion. Analogy: The electrical circuit-breakers in your home are fail-safe switches using this concept. In the case of an electrical fault causing a short, the circuit breaker will blow open, halting the flow of electricity. This prevents a fire from starting.
http://linux.about.com/cs/linux101/g/fail-safe__fail.htm


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Note added at 2日4時間 (2008-10-02 08:40:23 GMT) Post-grading
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回答として"fails openの誤記"と入力したところ、何故か"fails openの"で後が消えてしまいました。

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Note added at 2日5時間 (2008-10-02 09:34:14 GMT) Post-grading
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"RTA circuit breaker fails colsed."が誤記でないとしてこれを文法的に解釈しますと、"RTA circuit breaker fails to be colsed."の"to be"が省略されたものと考えるしかないでしょう。