It is a motor structure that does not produce arcs, sparks, or dangerous high temperatures under normal operating conditions, and additional mechanical, electrical, and thermal protection measures are taken to further avoid the danger of arcs, sparks, or high temperatures under normal or recognized overload conditions, thereby ensuring its explosion-proof safety.

The basic series of low-voltage increased safety type currently used in our country is the YA series increased safety type three-phase asynchronous motor, which is a derivative product of the Y series (IP44) three-phase asynchronous motor. The explosion-proof performance meets the requirements of GB3836.1-83 "General Requirements for Explosion-Proof Electrical Equipment for Explosive Environments" and GB3836.3-83 "Increased Safety Electrical Equipment 'e' for Explosive Environments"; the power range is 0.55~90kW, with corresponding frame center heights of 80—280mm; the explosion-proof marks are eIIT1, eIIT2, eIIT3, which are suitable for places with temperature groups T1—T3 explosive mixtures and slightly corrosive media in factories; the protection level of the main shell is IP54, and the protection level of the junction box is IP55; the rated frequency is 50Hz, and the rated voltage is 380V; the motor uses F-class insulation.

The main models of the derived series of low-voltage increased safety motors include: YASO series small power increased safety type three-phase asynchronous motors (with frame center heights of 56—90mm), YA—W, YA—WFl series outdoor and indoor anti-corrosion increased safety type three-phase asynchronous motors (with frame center heights of 80—280mm).

Ge Wu has completed the industry joint design work of the YA2 series and is organizing trial production to replace the YA series. The YA2 full series has a total of 15 frame numbers (with frame center heights of 63—355mm) and a power range of 0.12—400kW, which will bring our increased safety motors to the advanced level of similar products in the 1980s internationally.

The high-voltage (6kV) increased safety type three-phase asynchronous motor series includes: YA355—450, power 160—450kW; YA560—900, power 500—1800kW; YAm355—630 water-cooled, power 220—2500kW; YAKK355~630 air-to-air cooled, power 185—2000kW. The TAKW4000—20/2600, 4000kW increased safety type brushless excitation synchronous motor, which was trial-produced in 1999, is a new type of explosion-proof motor developed to meet the needs of hydrogenation devices in oil refineries.

Its main features are:

(1) Meets the requirements of increased safety explosion-proof motors, taking a series of reliable measures to prevent sparks, arcs, and dangerous high temperatures, and can safely operate in Zone 2 explosive hazardous locations.

(2) Uses brushless excitation, with a rotating rectifier disc and static excitation cabinet, and a reliable excitation control system; the positive polarity slip throw-in is accurate and without impact; the excitation system has reliable out-of-step protection and strong re-stepping capability; the circuit design is reasonable, and the discharge resistance does not heat up during operation; the excitation current adjustment range is wide.

(3) The synchronous machine, AC excitation machine, and rotating rectifier disc are coaxial. The rectifier disc is located between the main motor and the excitation machine or outside the bearing seat.

(4) The protection level of the shell is IP54.

(5) Uses F-class insulation, with temperature rise assessed according to B-class standards.

(6) Changes the traditional lower water cooling to upper water cooling, that is, the water cooler is placed at the top of the motor.

(7) Equipped with an increased safety type dehumidifying heater, fixed inside the cover at the bottom of the motor, used for heating to prevent moisture during downtime.

(8) Selects high-quality raw materials, with sufficient margins in electrical and mechanical calculations, to meet the reliability of operation and temperature requirements of increased safety motors.

(9) Equipped with comprehensive monitoring measures; the main junction box is equipped with an increased safety type self-balancing current transformer for differential protection; the stator winding is embedded with working and standby platinum resistance thermometers, with a scale number of Pt100; a water leakage monitoring instrument is set to monitor the leakage of the water cooler; both ends of the pedestal sliding bearings are equipped with on-site temperature display instruments and remote signal terminals.