DE8808813U1 - Standstill heating for a closed electrical machine - Google Patents

Description

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Siemens AG

Standstill heating for a closed electrical machine 5

The innovation relates to a standstill heater according to the preamble of claim 1.

Such standstill heaters, designed to maintain the internal temperature slightly above the external temperature when the machine is at a standstill in order to avoid condensation and condensation, are known from the Siemens operating instructions NMA2821DE/1753.5N and contain partially ring-shaped bent heating rods on retaining rings, which are either inserted in the bearing shield centering in the stator housing and fixed by the bearing shield or clamped as expansion rings in the bearing shield centering or held in the grooves in the case of internal axial cooling fins with turned-in grooves.

Since certain minimum air gaps must be maintained between the live stator winding and the heating wires of the heating rods for safety reasons, an axially extended stator housing corresponding to the dimensions of the anti-condensation heater is required for such machines.

The innovation is based on the task of achieving the required air gaps in closed machines with axially extended and inwardly partially open channels between the stator housing and the stator core, as known from EP-A-O 190 602, without an axially extended stator housing and of being able to use uniform distance heaters for different machine sizes.

Ot 2 Th / 29.06.1986

88 6 3 2 7 8 EN

The solution to the problem is achieved by the characterizing features of claim 1.

Further details of the innovation are the subject of separate claims.

An example of an embodiment is shown in the drawing and is explained in more detail below. They show:

FIG 1 shows a cross-section along the line I-I of FIG 2 through a stator housing with four axial channels covered on the outside, of which the two lower channels are covered by baseboards.

FIG 2 shows a longitudinal section along the line H-II of FIG 1; FIG 3 shows a detail of the object according to FIG Ij

FIG 4 shows an assembly unit comprising a heating element and holding devices including a separate holding ring for the heating wire ends in a perspective view in association with a channel according to FIG 1; FIG 5 is a plan view of an assembly unit according to FIG 4; FIG 6 is a partial side view of the object according to FIG 5j

FIG 7 shows a cross section along the line VII-VII in FIG 5 and FIG 8 shows a slotted retaining ring with a pushed-on connecting sleeve.

In all figures, corresponding parts are provided with identical reference symbols.

According to FIG 1, between four cooling fin arrangements indicated by dashed lines, each with parallel cooling fins, four channels with a continuous trapezoidal cross-section are arranged, which are closed off to the outside and are open to the inside in the end area of the stator housing 2 and are separated from the not shown. The

88 B 3 2 7 8 D£

^x ' 1 both lower channels are covered by baseboards, of which at least one channel 3 accommodates a standstill heater 1. One upper channel can be covered with a covering terminal box (not shown) and the other channel 3A with a connection box for the standstill heater (also shown as sealed), to which the free ends of the heating wires IB are laid at a distance from the connection in a way that prevents arcing from the stator winding. The heating wires IB are sealed and led out of the ends of elongated tubular heating elements IA of the standstill heater 1, which are bent into a "U", and are wound upwards around a retaining ring 4 arranged concentrically to the inner wall of the stator housing up to the channel 3A. The open retaining ring 4 is inserted in the vicinity of the anti-condensation heater 1 in annular grooves of axial internal cooling fins of the stator housing and is fixed in the inserted state by a squeezable, pushed-on connecting sleeve 6 at the joint according to FIG 3.

The heating wire ends are fixed on the retaining ring 4 in a defined position relative to the live machine parts.

The tubular heating elements IA are held together at both end areas by a holding arrangement 7 and a holding bracket θ to form an assembly unit which can be pushed as a whole from the radial opening into the respective channel 3 and is screwed axially to the holding bracket 8 on the inside of an annular shoulder of the stator housing by a holding screw 9. The other end of the assembly unit is held sufficiently firmly in the channel 3 in the clamp fit by the holding arrangement 7.

3u The holding arrangement 7 consists of two holding plates 7A arranged between the tubular heating elements IA and a spring -loaded clamping bracket 7B of approximately V-shaped design arranged between them and projecting on both sides. The tubular heating elements IA are held by holding brackets 5 ¹ which are connected by continuous holding screws

88 6 3 2 7 8 EN

<« HII ·· >

III I · I

I I J » · I

I I 4 II

5A (FIG. 7) are held pressed against the tubular heating elements IA, whereby the screw pressure also fixes the required spreading of the curved end regions of the clamping bracket 7B to the clear inner width of the channel.

The ends of the tubular heating elements IA are pressed by means of screwable retaining tabs 5 ¹¹ onto the retaining bracket 8 in the area of a transversely widened fastening surface &THgr;&Bgr;, the angled front surface 8A of which projects beyond the end of the tubular heating elements IA and is connected by means of the retaining screw 9 to the connection flange for front-side bearing shields (not shown).

When the pressure on the retaining tabs 5' and the retaining plates 7A is released, the spring-loaded clamping bracket 7B can be moved in the longitudinal direction of the heating rods between the retaining screws and can be adjusted to the respective internal dimensions of the channel 3 in such a way that the clamp ends always exert a sufficient pressing force on the inner walls of the channel, which is necessary for the immovable position of the assembly unit.

If an expandable retaining ring 4 is omitted, the wire ends can also be fixed directly to the inside of the stator housing, which is provided for stator housings with smooth inner surfaces.
25

3 Protection claims
8 figures

Claims (3)

88 6 3278 DE Protection claims 1. Standstill heating for a closed electrical machine with tubular heaters detachably held in the stator housing bodies in conjunction with a slotted retaining ring, whereby the connection ends of the heating wires, which are led out of the tubular heating element in a moisture-proof manner, are laid inside the stator housing to lockable connection boxes accessible from the outside in a flashover-proof manner, characterized, that in the case of stator casings with axial channels that are open inwards in the end area and closed on the outside for the covering attachment of skirting boards and/or connection boxes at least one elongated, U-shaped tubular heating element (IA) with an end holding arrangement (7) and a end-side retaining bracket (8) are combined to form an assembly unit which is inserted into at least one channel (3) at the front, which is held in the channel (3) in a force-fitting manner at the end by means of the retaining arrangement and by means of the retaining bracket (8) connection end is loosely attached to the stator housing. 2. Standstill heating according to claim 1, characterized in that the longitudinally extended tubular heating elements (IA) are held with their connection-side end region on a laterally widened fastening surface (8B) of a holding bracket (8) with its angled front surface (8A) projecting beyond the end region by means of screw-on holding tabs (5 ^M ) and are pressed with their connection-free end region onto two holding plates (7A) by means of holding tabs (5 ¹ ) and holding screws (5A) and between the two holding plates (7A) and the holding screws (5A) a spring clamping bracket (7B) projecting laterally with its ends beyond the tubular heating elements (IA) is held adjustable to the clear width of the channel (3). 35 88 G 32 7 8 OE 3. Standstill heating according to claim 1, characterized, that the heating wires (IB) of the tubular heating elements (IA) that lead out are guided on a slotted retaining ring (4) that is spread apart in the stator housing (2) up to a channel (3A) for a connection box, at a safe distance from live machine parts, and the slotted retaining ring (4) is spread apart to the respective internal dimensions of the stator housing by means of a squeezable connecting sleeve (6) that connects at the end.