Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H9/00—Details
  • F24H9/18—Arrangement or mounting of grates or heating means
  • F24H9/1854—Arrangement or mounting of grates or heating means for air heaters
  • F24H9/1863—Arrangement or mounting of electric heating means
  • F24H9/1872—PTC
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F24—HEATING; RANGES; VENTILATING
  • F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
  • F24H3/00—Air heaters
  • F24H3/002—Air heaters using electric energy supply
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
  • H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
  • H05B3/26—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base
  • H05B3/265—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor mounted on insulating base the insulating base being an inorganic material, e.g. ceramic
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/20—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater
  • H05B3/22—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible
  • H05B3/28—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material
  • H05B3/283—Heating elements having extended surface area substantially in a two-dimensional plane, e.g. plate-heater non-flexible heating conductor embedded in insulating material the insulating material being an inorganic material, e.g. ceramic
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K7/00—Constructional details common to different types of electric apparatus
  • H05K7/20—Modifications to facilitate cooling, ventilating, or heating

Definitions

• Present invention relates to an electrical convective heater which is used especially in automation panels and similar small cabinets for warming the environment as well as controlling the humidity therein.
• the present invention is applicable in the field of electrical and electronical control and automation panels.
• Fig. 1 is the upper cross-sectional view of a convective panel heater produced in accordance with the invention.
• Fig. 2 is the schematic top view of the a heater plate within a convective panel heater produced in accordance with the invention.
• Fig. 3 is the schematic perspective view of the aluminum body of the convective panel heater produced in accordance with the invention.
• Fig. 4 is the dismantled view of the sandwich heater plate of the convective panel heater produced in accordance with the invention.
• Fig. 5 is the cross-sectional view of the sandwich heater plate of the convective panel heater produced in accordance with the invention
• Fig. 6 is the schematic top view of the indented plate of the sandwich heater plate of the invention.
• the invention relates to a control-automation panel heater which comprises a sandwich heater plate placed inside a convective aluminum based body.
• the aluminum based body (3) is in the shape of a rectangular prism which has inner channels that permit air flow in order to realize convective heating.
• the sandwich heater plate is placed inside a groove (5) which is preferably recessed in the mid-part of the body. Upon applying electric current onto the sandwich heater plate, the plate and the body (3) which is in direct contact with the plate, starts heating.
• the heated body (3) is preferably mounted vertically in the environment to be heated. Air flow occurs through the channels on the vertically mounted body. As the temperature of the air increases the air moves upwards through the channels and an air current forms inside the channels and a circulation around the body. This air movement may be in the shape of natural convection as well as forced convection.
• Said body (3) is in a preferred embodiment of the invention preferably produced of black eloxal aluminum whose heat transfer coefficient is fairly high.
• a clips may also be attached at the back side of the body (3) for easy-mounting onto bars inside cabinets.
• Sandwich heater plate is an essential feature of the invention.
• Sandwich heater plate has a composite structure formed by winding a resistance wire (4) over an indented mid-plate (1) and covering the top and the bottom sides of said indented plate (1) with similar insulative plates (2. a, 2.b).
• the width of the heater plate (1) which is widely wound with the resistance wire (4) is smaller than the width of other plates (2.a,2.b) at all locations where resistance wire (4) is wound.
• Said insulative plates (1, 2. a, 2.b) are preferably produced of mica laminate material in the preferred embodiment.
• mica laminates are preferable as insulative plates for they provide perfect electrical isolation even at very high temperatures around 1000°C and they are also very easy to treat during manufacturing.
• Dielectric resistance of mica laminates are typically higher than 20 kV/mm. Insulation resistance of this material at 500°C is higher than 1x10 12 ⁇ x cm.
• Other types of materials which have good properties like mica laminates may also be used in the production of insulative plates.
• resistance wire (4) is wound onto the indented heater plate (1) located in the middle of the sandwich structure.
• the parameters for selecting the resistance wire depends on the desired power of the heater. Heaters for control/automation panels disclosed by the invention operate roughly in the 0-440 V voltage range and 30-200 watt power range.
• the resistance wire (4) which is wound onto the mid-insulative heater plate (1) is preferably selected among Cr-AI-Si-Mn alloyed wires. The reason behind is the high temperature resistance of these even at 1500°C. Their resistances change generally in the 120- 150 m ⁇ cm range.
• the properties and length of the wire which is to be used in winding the heater plate (1) can be determined after determining the desired panel heating power and the number of heaters.
• Resistance wires (4) wound on the heater plate (1) of the invention shall be wound with constant pitch as to avoid any contact between each subsequent winding.
• the purpose is clearly to avoid any hot-spots originating from short-cuts and consequently any irregularity in the heating distribution. It has been found that a regular heating regime can be maintained by leaving at least 0.5 mm constant gap between each winding.
• Sandwich heater plate shall preferable be fitted in a metal based body in order to achieve satisfactory convection.
• a current jump may be in the form of either a physical contact between the resistance wire (4) and the metal body (3) or an arc in between the body and the resistance wire immediately in the vicinity of the body.
• a good insulation between the body and the sandwich heater plate shall be maintained for assuring elimination of such a risk. Otherwise, leakage current may be incurred on the control/automation panel which brings the risk of damage to the instruments on the panel as well as risk of electric shock to humans operating in the region of said automation panels.
• mid-insulative plate (1) of mica laminate material is at first cut in a rectangular shape. Thereafter, the rectangular laminate is further cut to indent at least 1 mm towards the centeriine which is parallel to the longer sides and the final shape shown in Fig. 6 is maintained. Resistance wires (4) are then wound over the indented narrow profile. This indentation eliminates the risks of a contact or an arc between the resistance wires (4) and the metal body (3) in the groove (5). As shown in Fig. 5, resistance wires (4) are wound around the indented heater plate (1) but they do not extend to the edges of the sandwich heater plate.
• the resistance wire (4) is wound longitudinally around the indented heater plate (1) starting from the front part towards rear part leaving regular gaps between each subsequent winding.
• the rear end of the wire (4) remains at the front part of the plate (1) whereas the front end of the same wire is moved back to the front part of the plate following the end of last winding on the back part of the plate (1).
• the front end of the wire (4) then passes through a hole drilled on the front part of the plate (1) and brought next to the rear end of the wire.
• the rectangular bottom and the top insulating plates (2.a, 2.b) are then used to cover the upper surface and the lower surface of the indented heater plate (1) (Fig.4).
• the two ends of the resistance wire are then connected to two terminals attached to the front part of the panel (1).
• the heater which is produced by winding the resistance wire starting from the front part and ending at the rear part also creates also creates magnetic field while heating the panel.
• some of the very sensitive electronical equipments which might have been installed on the control/automation panel may be negatively affected from this induction zone created by the windings on the heater plate (1).
• the solution suggested by the invention is to wind the resistance wire both in the backward and forward directions on the indented heater plate (1).
• a backward winding subsequent to an initial forward winding may be accomplished in the following sequence; the winding of the resistance wire (4) starts at the front part of the heater plate (1) and as it is reaches the rear end of the winding area, the wire is not passed to the lower face of said plate, the front end of the resistance wire (4), which was brought to the rear part of the plate, is wound around the plate in the opposite direction towards the front part of the plate (1), the front tip of the resistance wire (4) which reaches the front part of the indented heater plate (1) is attached to the terminal next to the second tip of the wire.
• Opposite winding method helps to provide a non-inductive heater.
• the magnetic field which is created by the first winding i.e. forward winding
• the magnetic field created by the second winding i.e. backward winding
• the important point in preparation of the opposite winding is the fact that that all windings shall have enough clearance between each other such that no contact should be incurred between neighboring wires (4).
• the gap foreseen in the single direction windings shall be at least doubled in the initial forward winding in case a bi-directional winding is desired.
• a binder like silicon is added around the two ends of the heater plates in order to safely fix the plates in the groove (5). Insulating pipes are then dressed onto the terminals in order to finish the panel heater ready for electric appliance.
• the panel heater is installed on the bars of automation/control panels through use of a connection clips located on the aluminum body.
• the product is, upon connection to a thermostat, ready for use in the control of the temperature and humidity within the panel cabinet.
• the operation of the heater may directly be controlled by means of a thermostat.
• the convective panel heater comprising a sandwich heater inside a convective body, is useful as to its low surface temperature eliminating the risks of damage to the electric-electronic equipments and burnt risk to the humans as well as to its low cost.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Inorganic Chemistry (AREA)
• Surface Heating Bodies (AREA)
• Direct Air Heating By Heater Or Combustion Gas (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2002
  • 2002-07-01 AU AU2002321979A patent/AU2002321979A1/en not_active Abandoned
  • 2002-07-01 EP EP02756061A patent/EP1410706A2/de not_active Withdrawn
  • 2002-07-01 WO PCT/TR2002/000026 patent/WO2003005770A2/en not_active Application Discontinuation

Non-Patent Citations (1)

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