塑料外壳式断路器标准对比分析-英

Comparative Analysis of Criterion of Plastic Circuit Breaker

XuJun Cai

Xiamen HongMei Electric Limited Company

Abstract To develop plastic circuit breakers which is up to both the UL and GB standard, I list the differences between

UL489 and GB 14048.2(equal to IEC) on requirements of their structure, performance etc. by comparing.

The main basis for a circuit breaker are GB 14048.2 and UL 489(equal to IEC60947-2). The UL standard apply to the USA, Canada and Mexico. The IEC is a international standard, and lots of countries adopt the equivalent standard now, for example, Chinese GB, Japanese JIS, German VDE and British BS etc.. To improve our products to meet the Northern American market, we have to work out the differences between the UL standard and GB standard.

Standard comparison between UL489 and GB 14048.2

1.Application environment

GB 14048.2 is suitable to circuit breakers whose main contact is used to access into over 1000V a.c. or 1500V d.c. Circuit. UL 489is suitable to circuit breakers whose rated voltage is less than 600v and rated current is less than 6000A.

In China, low voltage distribution system usually adopt 380Y/220V a.c., so rated voltage of the current plastic circuit breaker should be 400V. But the NEMA standard it is stipulated that the rated work voltage should be: 120v, 127v, 120/240v, 240v, 277v, 480Y/347v, 480v, 347v, 600Y/347v and 600v. The general rated voltage of plastic circuit breakers used for the industry and commerce should be over 240V a.c. and the common values are 240v, 480v, 480Y/277v and 600Y.347v.

2.Clearance

In structure, UL 489 has higher requirement than the GB standard on clearance obviously. In GB 14048.2, it is just stipulated that the minimum clearance of a plastic circuit breaker in air should be 5.5mm and its minimum Creepage Distance should be

10mm. But in UL 489, it does the detailed provision to the different sectors of the breaker body, as seen in Table 1:

Tabale 1 Minimum spacings in millimeters from UL 489

3.Breaking Capacity

There is a large difference on breaking capacity between GB 140148.2 and UL 489, details as follows:

3.1 Short circuit breaking capacity

There are 2 types of short circuit tests stipulated in the GB 14048.2, service short circuit breaking capacity and ultimate

short-circuit turn off capacity. But there is only the specified current test required in UL 489, for a high breaking current, it is just stipulated that we might do a addable test according to breaking parameters of corresponding products.

As shown in table 2, the high breaking current test in UL489 has similar procedure to the ultimate short-circuit breaking test in GB14048.2.

Table 2 parallel table of breaking capacity test sequence