UL 875:2009 pdf download – Electric Dry-Bath Heaters
UL 875:2009 pdf download – Electric Dry-Bath Heaters.
30.3.5 The test covered in 30.3.1 is to be repeated in the same manner with approximately 50 percent of the heater top covered.
30.3.6 A heater intended to be supported by. and mounted away from a wall or ceiling in a horizontal position shall comply with 30.3.1 when tested In the intended position with a double layer of cheesecloth draped over the lull length of the heater and hanging down approximately 0.3 m (1 foot) on each side.
30.3.7 In a test to determine compliance with the requirement in 30.3.1. the Ian of a combination heater and motor-driven I an is to be operating when the heater is covered with cheesecloth.
30.4 Thermal cutoff
30.4.1 A thermal cutoff, when provided, shall open the circuit in the intended manner without causing the short-circuiting of live parts and without causing live paris to become grounded to the enclosure wtien the heater is connected to a circuit of voltage in accordance with 25.8 and operated as described in 30.4,2,
30.4.2 To determine thermal-cutoff compliance with the requirement in 30.4.1, the heater is to be operated five times, each with a new, separate thermal cutoff In the circuit as described in 30,4.1. and with any other thermally-operated control devices in the heater short-circuited. Each thermal cutoff is required to perform as intended. During the test, the enclosure is to be connected through a 3-ampere fuse to ground, and the thermal cutoff is to be in the ungrounded conductor of the branch circuit supply.
30.5 Stalled tan
30.5.1 A combination heater and motor-driven tan shall not constitute a risk of lire and shall not emit molten metal (other than melted solder) or flame with the fan stalled for a period of 7 hours, or until the manual-reset limit control operates.
30.6 Component breakdown
30.6 adc)ed Noven,e 16. 2011
30.6.1 When tested in accordance with 30.6.2, a simple control of 20B.4 having components – such as diodes, resistors, transistors, capacitors, and the like – with a single component fault of short or open, shall not result in any condition as specified in 30.1.1.
Exception No. 1: This lest is not required for circuits comp’ying with 21.1.3 or 21.1.4.
Exception No. 2: This test need not be conducted if the components have been investigated and found to have permanence and stability so as to not decrease their limiting capabilities. For the purpose of this test, capacitors connected across the output are not considered likety to open.
30.6.2 A sample Is to be connected to the maximum test voltage and operated until ultimate conditions are observed, or for 4 hours if cycling of an automatically reset protector occurs.
31 Motor Switch Overload Test
31.1 A switch or other device that controls a motor, unless intended for the application or interlocked so that it will never bi’eak the locked-rotor motor current, shall pertomi as intended when subjected to an overload lest consisting of 50 cycles of operation, making and breaking the locked-rotor current of the motor. The performance is not in compliance when the fuse in the grounding connection opens during the test, and there shall be no burning, pitting, or welding of the contacts that impairs the device’s intended function.
31.2 To determine that a switch (Or other control device) will perform as intended in the overload test, the heater is to be connected to a grounded supply circuit of rated frequency and of voltage in accordance with 25.8, with the rotor of the motor locked. Dunng the test, exposed dead metal parts of the heater are to be connected to ground through a 3-ampere fuse, and the current-rupturing device, when single-pole. is to be located in an ungrounded conducto4’ of the supply circuit. When the heater Is intended for use on direct current, or on direct current as well as alternating current, the test is to be conducted with direct current and exposed dead-metal parts are to be connected so as to be positive with regard to a single-pole, current-rupturing device. The device is to be operated at the rate of 10 cycles per minute.
Exception: A faster rate of operation is not prohibited from being used when agreeable to all concerned. 32 Stability Test
32.1 The stability of a heater intended to stand on the floor shall be such that it will not overturn when subjected to the tests descnbed in 322 and 34.1.
32.2 A floor-mounted heater shall not tip over when tilted 15 degrees from its intended, upright freestanding position with all doors, covers, trays, screens, rocks, rock holders, and the like in place, or in the most critical open servicing position. Fastening means are not to be used for this test.