ANSI UL 458 - Output Short-Circuit

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UL COPYRIGHTED MATERIAL –

NOT AUTHORIZED FOR FURTHER REPRODUCTION OR

DISTRIBUTION WITHOUT PERMISSION FROM UL

47.1.5 Each test is to be conducted on a separate sample unless the manufacturer requests that more

than one test be conducted on the same sample.

Exception: For the overload tests, one sample may be used provided it is subjected to the tests in the

following order: 200 percent of rated current, followed by short-circuit current.

47.1.6 A manually or automatically reset protector or other overload protective device in a converter or

inverter shall open the output circuit within 2 minutes after initiation of the test, and within 30 seconds for

subsequent cycles during the output-short-circuit, switch-position, and speciﬁc-value-overload tests.

Exception No. 1: The time required to open the output circuit may exceed the time speciﬁed provided the

maximum temperatures attained do not exceed the limits speciﬁed in Table 38.1 for ﬂush-wall mounted

units, or 20°C (36°F) more than that speciﬁed in Table 38.1 for ﬁxed or stationary stand-alone type units

surfaces, and 20°C (36°F) more than that speciﬁed in Table 37.1 for components and materials.

Exception No. 2: The switch-position test may be waived if with the transfer switch in the battery position,

the converter or inverter will not operate when connected as described for the input test – see Section 33,

Power Input Test – and no risk of ﬁre or electric shock is found to exist.

Exception No. 3: The time required to open the output circuit during the speciﬁc-value-overload test may

exceed the time speciﬁed provided the converter or inverter does not emit ﬂame or molten metal or

become a risk of ﬁre or electric shock while operating under the test condition described in 47.8.1 for 15

days.

47.1.6 revised January 27, 1995

47.2 Output short-circuit

47.2.1 The external output connections of a converter or inverter are to be short-circuited and the

converter or inverter is to be connected to a source of supply adjusted to the test voltage speciﬁed in

Table 31.1. The source of supply may be protected by a time-delay branch-circuit overcurrent-protective

device rated not less than 20 amperes. During the test, the enclosure is to be connected directly to earth

ground. A protective device such as an accessible fuse or circuit breaker provided as part of the converter

or inverter is to remain in the circuit, and the largest fuse the fuseholder will accept is to be installed.

47.2.1 revised January 27, 1995

47.2.2 For the test described in 47.2.1, fuses or circuit breakers provided for individual low-voltage

branch-circuit protection may remain in the circuit. If a fuseholder is provided, a fuse rated not less than

30 amperes is to be installed in the fuseholder. The short circuit may be applied across one individual

low-voltage circuit, which, for the purpose of this test, may employ output leads as described in 12.1.3

having a total length of 4 feet (1.22 m) that is, having positive and negative leads each 2 feet (610 mm)

long.

47.2.3 If acceptable results are based on the opening of an overcurrent-protective device, the

overtemperature-protective device shall be operable at the conclusion of the tests.

OCTOBER 15, 2004UL 45860B