|
UL 1412
q3 [) o* v4 h8 `# y15 Overload Test
# C4 ] `# ]% \3 `$ _5 \15.1 A resistor shall withstand the overload test described in this section without resulting in a fire.
+ D. n; \+ |/ j7 }' t15.2 A single layer of cheesecloth is to be wrapped around, and be in contact with, the resistor under test.
1 d% Z" X" k+ `, z; B' u, X# WException: At the manufacturer’s option, the cheesecloth may be spaced 1/2 inch (127 mm) – or 1 inch
7 O }+ W0 f$ a. h" n4 q. N(25.4 mm) for a resistor rated greater than 10 W – from the resistor body as described herein. In this case,
7 F$ `% `- \9 ^. X9 z" na positive spacing of 1/2 inch (or 1 inch, as appropriate) between the resistor body and combustible
8 r/ \! D$ T+ c3 w: pmaterials is to be provided in the complete appliance. A single layer of cheesecloth is to be placed around* d. s7 l4 [: g8 U% y! y/ N% l
the resistor under test to form a cylinder with open ends. The length of the cylinder is not to be less than1 D9 {4 {5 h2 Z% x5 ]
three times the length of the resistor body and the diameter of the cylinder is to be such that the5 Y3 H" z4 d* |' [# L- U% Z! {
cheesecloth is spaced 1/2 inch (or 1 inch, as appropriate) from the outermost part of the resistor body.5 l4 g! U/ \ L( z$ i
The resistor body is to be centered end-to-end within the cylinder and the longitudinal axis of the resistor; ~# \8 S g* ? `
body is to be coincident with the longitudinal axis of the cylinder.
( i7 H n9 j3 O2 L$ }15.3 The resistor is to be connected to a 60-Hz variable voltage source of supply fused at 30 A. Prior to
% g1 b' g4 D/ n; k( F% t6 Qenergizing, the supply voltage is to be adjusted to produce rated current (or rated power dissipation) in$ x( S% H/ c( r2 o- O
the resistor. At 1-minute intervals after energizing, the supply voltage is to be raised in steps of 2, 3, 4, 5,
! o3 O. j A7 P( A3 e6 u8 jand so forth, times that initial voltage until the resistor opens. In no case is the voltage rating of the resistor
6 F( L' e& S/ s! V" r+ eto be exceeded.
( I+ z" c. L! p, B0 X6 X# M$ v15.4 Five complete separate tests are to be made using new samples for each test.
( M: e1 X4 S3 B. e: U15.5 The results are not acceptable if the cheesecloth flames.5 P, c8 V6 l7 ?- O8 e$ l+ Q
15.6 The cheesecloth used for the overload test shall be untreated cotton cloth 36 inches (0.9 m) wide,
1 Z- F. o0 p: P* V4 j" C& yrunning 14 – 15 yd2 /lb and having what is known to the trade as a count of 32 by 28. |
|