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19.5 The test of 19.4 is repeated on class 0I appliances and class I appliances% t$ F2 w/ c+ x' d) N
incorporating tubular sheathed or embedded heating elements. However, controls are not
# Q' h8 q) E) I3 k* \6 G" Nshort-circuited but one end of the element is connected to the sheath of the heating element.8 b5 R5 w1 x7 k5 c- R! e
This test is repeated with the polarity of the supply to the appliance reversed and with the
5 s0 @( [- ?. {6 {other end of the element connected to the sheath.
# v2 O6 b n, A# n+ cThe test is not carried out on appliances intended to be permanently connected to fixed wiring 5 u! b4 {8 W% Y* \& s
and on appliances where an all-pole disconnection occurs during the test of 19.4.
, J v3 u2 d7 I3 q) D9 ~Appliances with a neutral are tested with the neutral connected to the sheath. 6 R! s3 D5 u1 Z- v. ]. M" @: s
NOTE For embedded heating elements, the metal enclosure is considered to be the sheath.+ ]* A! O, r- J& ^* Q1 o
什么意思三相三线的取暖器需要测试吗5 g4 L8 s& V# | t' }
怎么测试" y; z% N% f# {& A4 ?/ }
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