How to carry out concrete warming up by the transformer?
In winter time iskusstyovenny warming up is applied to protection of concrete from the promeryozaniye and acceleration of its skhvatyvaniye (steam, the electric power, the warm vozduyokh and also by means of the device of the facilitated teplyayok).
Owing to simplicity of implementation most широко the electrode way of warming up of concrete based on transformation of electrical energy to thermal is used.
At this way electrodes serve for inclusion of steel concrete or concrete designs in the chain of pereyomenny current. Heat is generated directly in the proyogrevayemy design and therefore the coefficient of polezyony action is higher, than at other spoyosoba.
At concrete electrowarming up usually use one or several reducing transformers. Transformers are most widely used: 20 kW single-phase TB-20, three-phase, 35 kW TB-35 and 50 kW TM-75/6 and also normal STE welding transformers with a power up to 32 kW.
So, at the scheme of turning on of 6 single-phase svarochyony transformers on windings of nizyoshy tension it is possible to receive at the same time tension: 65 — 112 V, 55 — 95 V or 70 — 120 Century.
As the operating mode of these transformers preyoryvisty, at their application for electrowarming up loading has to be no more than 75% of face value.
On buildings for concrete warming up also используются the ZTB-20 installations. Installation consists of 3 transyoformator of TB-20 and the combined raspredelitelyyony board in the metal box mounted on skids. The TB-20 transformer has the oil okhlazhyodeniye and from the highest tension can be attached to network by voltage of 220 V and 380 Century. From the storoyona of the lowest tension of the transformer it is possible to poluyochit 51 V or 102 Century.
In practice of construction the scheme of avtomayotizirovanny installation which allows to disconnect avtomatiyochesk electrodes from the power supply network at the dostizheyoniya in the warmed-up steel concrete design of preyodelny temperature is applied and to include them at its decrease. Automation of process of electrowarming up isyoklyuchat temperature increase in the design over that which is resolved on specifications, and sniyozhat the electric power expense. Such installation consists of the TB-20 transformer with a power of 20 kW and the oborudovayoniya mounted in the cabinet.
Automatic installation can be also the isyopolzovana at protection of foundations of the bases against the proyomerzaniye by means of electric heating elements and electroneedles. In this case installation allows to maintain avtoyomatichesk the set temperature in the sootyovetstviye with specifications.
On the way of laying in concrete electrodes separate on internal and surface. To internal rod and string longitudinal electrodes, to surface — strip strip and nashivny electrodes otyonositsya. As the electrode serves also the heating panel.
The ends of electrodes for accession of the wire of the dolzhyona on 50 — 60 mm to act from the design.
Rod electrodes produce from scraps of aryomaturny steel with a diameter of 10 — 12 mm. The scheme of the rasstanovyoka of rod and string electrodes is shown in fig. 1.
String longitudinal electrodes produce from aryomaturny steel with a diameter of 6 — 10 mm and put in concrete parallel links 2,5 — 3 m long.
Practice showed that the design gets warm most evenly when laying along it as equals distances from each other of 2-3 strings included in different phases of network.
Strip electrodes establish from the vnutrenyony party of the timbering, as shown in fig. 2.
Nashivny electrodes produce from round steel with a diameter of 6 mm or sheet steel 1,5 — 2 mm thick. Electrodes sew from the inside of the timbering at distance 100 — 150 mm one from another.
Heating panels (fig. 3) intend for warming up of plates of overlappings from 120 mm thick with the single armature; they represent the uteplenyony box from boards 25 mm thick which is filled up vnutyor with sawdust. On the lower party of the box nolosovye electrodes 60 — 80 mm wide and up to 3 mm thick, through intervals of 250 — 300 mm are strengthened.
Networks for the power supply of devices of electrowarming up have to be carried out by the cable or the insulated conductor. The site of warming up of concrete should be fenced, and in nochyony time to light.
Barriers have to be referred from extreme electrodes on distance not less than 5 mm.
On barriers hang out posters, predostereyogayushchy about danger of defeat by electric current. Besides, the zone of electrowarming up of concrete is equipped with the signal electric lamps which are lighting up when giving tension on concrete electrowarming up installation.
Electrical equipment, radio engineering bases, methodical grants and is a lot of other useful information - for those who want to understand this area independently.
On the site of electrowarming up the napryazheyoniya razreyoshatsya to make watering of concrete only after shutdown.
All service personnel working at the elekyotroprogreva have to be provided with dielectric galoshes and gloves.
In the zone of electrowarming up included in network it is allowed to go and transport concrete only on the special courses and scaffolding.Top