What Is a Calibrated Camera?

The camera is a kind of in-situ reactive power compensation device specially designed and manufactured for large and medium-sized wire-wound asynchronous motors. The camera has a rotor that resembles a DC motor, that is, an armature with commutators and windings, but the rotor slot is deep in the closed slot below its surface. The magnetic flux generated by the winding can be closed around the slot. The stator magnetic circuit is completely eliminated. Three-phase brushes are provided on the commutator every 120 ° to be connected to the rotor circuit of the main asynchronous motor. The rotor of the camera is dragged by a separate auxiliary motor.

The camera has a rotor that resembles a DC motor, that is, an armature with commutators and windings, but the rotor slot is deep in the closed slot below its surface. The magnetic flux generated by the winding can be closed around the slot. The stator magnetic circuit is completely eliminated. Three-phase brushes are provided on the commutator every 120 ° to be connected to the rotor circuit of the main asynchronous motor. The rotor of the camera is dragged by a separate auxiliary motor.

After entering the camera for a period of time, a large ring spark is generated, the surface of the commutator is blackened or even burned into a pit. Continuing to use it will cause a vicious cycle, cause damage to the camera, and endanger the safe operation of the main winding motor. . Take FZ-2 camera as an example, the commutator

Malfunctioning start, that is, when the camera is not started, the double-headed brake knife is in the "input" position, starting the mill motor, causing the mill to start directly, and the rotor of the mill motor burns the circumferential surface of the commutator. Its circumference is divided into six equally divided cautery pits, causing vibration or unevenness of the commutator when the commutator is running. At this time, the commutator needs to be processed on a lathe, but not more than one, otherwise it will affect the service life. After turning the commutator, the insulating mica sheet between the commutator sheets should be engraved downward and used. Glass sandpaper polishes the surface of the commutator under no-load operation.

(1) The armature's dynamic balance is poor, and the camera body vibrates, so that the brush cannot closely cooperate with the surface of the commutator; when the brush jumps, sparks are generated, and the surface of the commutator is burned. At this time, you should check whether the screws of the base of the camera body are loose; whether the concrete foundation is stable, and correct the dynamic balance of the armature to eliminate the vibration phenomenon during the operation of the camera.

(2) Individual commutator segments are hot and have significant sparks, which can be divided into two cases: A. The armature winding is broken or the winding to the commutator joint is poorly welded, the normal commutation is damaged, so, at this disconnection Sparks and overheating are generated on the commutator connected to the windings with poor connections or joints. If the naked eye can't judge or find the defects, the instrument can be used to measure the DC resistance value, such as double-arm bridge measurement. B. The armature winding is partially short-circuited; it will cause the winding to heat up. At the same time, the bridge can be used to measure the short-circuit location. The copper powder and carbon shavings between the commutator segments can be carefully removed. If the problem cannot be solved, the slot should be considered. If the winding is short-circuited, turn the wire to check and repair it.

(3) The individual brushes are stuck in the brush box, which deteriorates the close matching conditions between the brushes and the commutator, so that sparks are generated under the brushes, and part of the commutator surface is burned. At this time, the sides of the brushes should be sanded with sandpaper. Go for some so that the brush can slide up and down (but not shake) in the brush box.

(4) Dirt or poor contact at the connection of individual brush lead wires makes the current distribution between the brushes in the same row uneven, and the overloaded brushes generate sparks. At this time, you can loosen the connection and carefully clean the contact to make the connection. Good contact everywhere. When the lead wire and the brush are not in good contact, it will cause the current of other brushes adjacent to it to overshoot and cause the brush to overheat. At this time, the lead wire should be replaced due to overheating and discoloration.

(5) The pressure of the brushes in a row is not uniform, causing individual brush currents to be too large to cause sparks. At this time, the constant voltage spring should be replaced to adjust the brush stress. The contact surface of the brush and the commutator must not be less than 8000, otherwise Grind the brush.

(6) The brushes are not aligned in a row and are not aligned with the commutator, which increases the number of short-circuited components of the brush and causes sparks. At this time, the brushes should be aligned on the edge of the commutator. ^[2]

(1) The brush holder is loose and skewed, exceeding the allowable range, causing a strong spark under the brush, and the commutator surface is burned and blackened. At this time, the position of the brush holder is corrected, and the brush edge is aligned with the commutator.

(2) During the installation and wiring, the relative positions of the brush rods were changed, so that six brush rods were distributed unequally on the circumference of the commutator, and some of the brushes exceeded the range of the commutator to cause sparks and burn the surface of the commutator to cause Blackening, at this time, the bisector angle of the brush set is corrected, and the brush is perpendicular to the surface of the commutator.

(3) After using for a long time, carbon powder or other debris is accumulated in the mica tank, causing the commutator to overheat and slight sparks, and the surface of the commutator gradually scales and turns black. At this time, use a saw blade to pull the mica. The carbon powder or sundries in the tank are about 1mm deep.

(4) The wrong brush brand may cause the following situations: A. The brush current density is too high, and the brush is overheated to damage the surface of the commutator; B. The brush is too hard, causing the commutator to wear out prematurely, Grooves appear, and the surface of the commutator is damaged due to the frictional overheating of the brushes; C. The low resistivity of the brushes destroys the normal commutation conditions and generates sparks.

In the above cases, you should replace the brush of a suitable brand or use a brush produced by a designated factory.

(5) There are oil stains on the surface of the commutator, or there are small scars, etc., which cause poor conductivity and cause the commutator to overheat and become black. At this time, carefully clean the slots between the commutator plates and clean the commutator with alcohol. The surface is polished with No. 0 sandpaper.

In short, the above-mentioned situations are faults that occur during operation after the camera is installed. Of course, before installing into the camera, you should read the product manual carefully to check whether the data on the nameplate of the camera matches the current of the main motor rotor, so as to be prepared.