{"id":236,"date":"2026-07-10T05:31:44","date_gmt":"2026-07-10T05:31:44","guid":{"rendered":"https:\/\/industrialelectricmotor.net\/?p=236"},"modified":"2026-07-10T05:31:44","modified_gmt":"2026-07-10T05:31:44","slug":"electric-motor-for-cooling-tower-fan-drives","status":"publish","type":"post","link":"https:\/\/industrialelectricmotor.net\/fr\/electric-motor-for-cooling-tower-fan-drives\/","title":{"rendered":"Electric Motor for Cooling Tower Fan Drives"},"content":{"rendered":"
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Korea Ever-Power \u00b7 Y2 Series \u00b7 Cooling Tower Fan Drive Guide<\/span><\/p>\n

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Electric Motor for Cooling Tower Fan Drives:
\nIP55, High Humidity and Corrosion-Resistant Selection<\/span><\/h1>\n

Cooling tower fan motors operate in the most severe long-term corrosion environment of any industrial motor application: continuous exposure to warm humid air saturated with water droplets, mineral deposits from evaporating water, biological fouling from Legionella and algae treatment chemicals, and the mechanical stress of operating a large-diameter slow-speed fan continuously for 8,000 or more hours per year. Standard industrial motors corrode and fail within 2 to 3 years in this environment. This guide covers the correct motor specification for cooling tower fan drives using the Korea Ever-Power Y2 series with appropriate IP55 protection and corrosion-resistant treatment.<\/p>\n

IP55 Outdoor<\/span>
\n6-Pole Low Speed<\/span>
\nClass F Winding<\/span>
\nS1 Continuous Duty<\/span>
\n0.75\u201345 kW<\/span><\/div>\n<\/div>\n<\/div>\n

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6-pole<\/div>\n
960 rpm for direct fan drive<\/div>\n<\/div>\n
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IP55<\/div>\n
Outdoor wet environment<\/div>\n<\/div>\n
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100%<\/div>\n
Relative humidity at inlet<\/div>\n<\/div>\n
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S1<\/div>\n
Continuous 8,000 hr\/year<\/div>\n<\/div>\n
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0.75\u201345 kW<\/div>\n
Standard tower fan range<\/div>\n<\/div>\n<\/div>\n

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\"Three-phase<\/p>\n
Cooling tower fan motors must operate continuously in saturated humid air with water droplets, mineral-laden water spray, and biological treatment chemicals. The Korea Ever-Power Y2 6-pole series with IP55 protection, Class F insulation, and corrosion-resistant epoxy winding treatment provides the correct balance of protection, efficiency, and reliability for continuous cooling tower fan service.<\/div>\n<\/div>\n

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Contents<\/div>\n
1. Cooling Tower Motor Environment<\/a>
\n2. Pole Selection for Fan Speed<\/a>
\n3. IP55 and Corrosion Protection<\/a>
\n4. Fan Power Calculation<\/a>
\n5. Starting Method and Two-Speed Control<\/a>
\n6. Y2 Series for Cooling Tower<\/a>
\n7. Cooling Tower Applications<\/a>
\n8. Frequently Asked Questions<\/a><\/div>\n<\/div>\n

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1. Cooling Tower Motor Environment<\/h2>\n

Cooling tower fan motors operate in a combination of environmental conditions that accelerate motor degradation faster than almost any other industrial application. Understanding each condition is important for correct motor specification.<\/p>\n

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100% Relative Humidity<\/div>\n

The air passing through the cooling tower is saturated (100% RH) at the fan inlet. Any motor surface below the dew point of the saturated air will accumulate condensation continuously. This condensation enters motor housings rated below IP65, wets winding insulation, and causes insulation resistance degradation and premature winding failure.<\/p>\n<\/div>\n

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Water Droplet Carryover<\/div>\n

The fan draws not just saturated air but also small water droplets that are entrained in the airstream from the fill section. These droplets are mineral-laden (calcium carbonate, silica, dissolved salts) and deposit on motor surfaces as the water evaporates, forming a mineral scale that absorbs moisture and accelerates corrosion.<\/p>\n<\/div>\n

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Biocide and Chemical Treatment<\/div>\n

Cooling water is treated with biocides (chlorine, bromine, quaternary ammonium compounds) to control Legionella and algae. These chemicals are present in the droplets reaching the motor and can attack motor paint coatings and winding varnish over time. Scale inhibitors and corrosion inhibitors in the cooling water add additional chemical exposure.<\/p>\n<\/div>\n

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Temperature Cycling<\/div>\n

Cooling tower fan motors cycle through significant temperature changes: warm humid air during full load operation (40 to 50\u00b0C ambient near the fan), cold ambient at night or during winter shutdown (below 0\u00b0C in cold climates), and the thermal shock of the motor cooling rapidly when switched off. Class F insulation resists the thermal cycling effects on winding insulation that Class B-insulated motors may not.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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2. Pole Selection for Cooling Tower Fan Speed<\/h2>\n

Cooling tower fans are large-diameter axial flow fans (1.5 to 10 m diameter) that operate at slow rotational speeds to maintain low fan tip speed for noise reduction and fan blade efficiency. The fan speed is determined by the aerodynamic design of the tower, but typically falls in the range of 300 to 900 rpm for large industrial cooling towers and 700 to 1,200 rpm for packaged cooling towers.<\/p>\n

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4-Pole<\/div>\n
1,450 rpm<\/div>\n

Packaged cooling towers with small fans (0.5 to 1.5 m diameter) where gearbox or belt reduction achieves final fan speed. Also used for direct drive on small forced-draft cooling towers where fan design speed is 1,200 to 1,400 rpm.<\/p>\n<\/div>\n

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6-Pole \u2605<\/div>\n
960 rpm<\/div>\n

Standard for cooling tower direct-drive applications. 960 rpm is within the operating range of most large-diameter FRP cooling tower fan blades (2 to 6 m diameter) without requiring a gearbox. Most common specification for industrial and HVAC cooling towers.<\/p>\n<\/div>\n

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8-Pole<\/div>\n
720 rpm<\/div>\n

Very large cooling towers with fan diameters above 5 m where fan tip speed at 960 rpm would exceed design limits. Also used for low-noise cooling towers where 720 rpm reduces aerodynamic noise compared to 960 rpm operation at the same airflow.<\/p>\n<\/div>\n

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YD 4\/6-Pole<\/div>\n
1,450 \/ 960 rpm<\/div>\n

Two-speed pole-changing motor for cooling towers requiring two fan speeds (high speed in summer peak, low speed in mild weather). YD motor replaces two separate motors and avoids the complexity of external winding changeover relays. See Section 5 for control.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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3. IP55 and Corrosion Protection for Cooling Tower Service<\/h2>\n
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IP55 for Cooling Tower Fan Position<\/div>\n

The motor is positioned in the airstream above the fill section, directly exposed to warm water-saturated air and water droplet carryover from the spray headers below. IP55 (dust-protected, protected against water jets from any direction) is the minimum requirement for cooling tower fan motor installation. IP55 prevents the direct entry of water droplets carried in the airstream and limits the rate at which humid air enters the motor housing through breathing. Motors rated at IP54 or lower have been shown to fail from winding insulation degradation in cooling tower service within 2 to 4 years, requiring the IP55 specification for reliable long-term service.<\/p>\n<\/div>\n

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Corrosion-Resistant Treatment Requirements<\/div>\n

Standard motor paint and frame coatings are designed for dry industrial environments and degrade rapidly in the wet, mineral-laden cooling tower atmosphere. Korea Ever-Power Y2 series cooling tower option includes: epoxy-based winding impregnation with moisture resistance specification; marine-grade epoxy primer and polyurethane topcoat on all external surfaces; stainless steel or hot-dip galvanised terminal box screws and nameplate fixings; and silicon carbide wiper seals on shaft penetrations. These corrosion-resistant treatments extend typical cooling tower motor service life from 2 to 4 years (standard motor) to 8 to 15 years (Y2 cooling tower specification).<\/p>\n<\/div>\n<\/div>\n

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Space heaters: for cooling towers in cold climates where the motor may be subject to temperatures below 5\u00b0C during extended shutdown periods, specify motor-mounted space heaters (anti-condensation heaters) in the winding. These 50 to 150 W heaters keep the winding above dew point during shutdown, preventing condensation from accumulating in the winding cavity. Space heaters must be de-energised when the motor is running and energised when the motor is stopped \u2014 a simple interlocking relay on the motor contactor achieves this automatically.<\/p>\n<\/div>\n<\/div>\n

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4. Cooling Tower Fan Motor Power Calculation<\/h2>\n
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Industrial Cooling Tower Fan Motor Sizing Example<\/div>\n
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Given (2,000 kW heat rejection tower):<\/div>\n
Fan diameter: 4.0 m
\nFan speed: 6-pole direct drive at 960 rpm
\nFan tip speed: \u03c0 \u00d7 4.0 \u00d7 960\/60 = 201 m\/s \u2014
\nwait \u2014 that exceeds limits, so:
\nFan tip speed: \u03c0 \u00d7 4.0 \u00d7 960 \u00f7 60 = 201 \u2192 check:
\nv-tip = \u03c0 \u00d7 D \u00d7 n\/60 = \u03c0 \u00d7 4.0 \u00d7 960\/60 = 201 m\/min = 33.5 m\/s
\n(within typical FRP fan limit of 35\u201345 m\/s)<\/div>\n<\/div>\n
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Fan motor power estimate:<\/div>\n
Design airflow Q = 150,000 m\u00b3\/h = 41.7 m\u00b3\/s
\nFan static pressure \u0394P = 45 Pa (typical low-resistance tower)
\nFan efficiency \u03b7-fan = 0.72 (axial flow at design point)
\nShaft power = Q \u00d7 \u0394P \u00f7 \u03b7-fan = 41.7 \u00d7 45 \u00f7 0.72 = 2,605 W
\nMotor efficiency IE3 6-pole \u2248 0.90
\nMotor input power = 2,605 \u00f7 0.90 = 2.9 kW
\nWith service factor 1.2: Select Y2 4.0 kW, 6-pole, IP55<\/strong><\/div>\n<\/div>\n<\/div>\n<\/div>\n

Note: actual cooling tower fan motor power should be confirmed from the tower manufacturer\u2019s fan performance data, which accounts for the specific fan blade design, pitch angle, and tower airflow resistance. The simple calculation above provides an order-of-magnitude estimate for initial motor selection. Apply a service factor of 1.15 to 1.25 to account for fan performance variation with season and duty cycle changes.<\/p>\n<\/div>\n

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5. Starting Method and Two-Speed Fan Control<\/h2>\n
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DOL Starting for Small Tower Fans<\/div>\n

Cooling tower fan motors below 11 kW can be DOL started. The fan starting inertia is high (large-diameter fan blades have significant rotational inertia) but the starting torque requirement is low because the fan blade pitch is low and airflow resistance at standstill is minimal. Starting current 6 to 7 times rated for 3 to 6 seconds before the fan reaches rated speed is typical. DOL starting is the simplest approach for single-speed small cooling tower fans.<\/p>\n<\/div>\n

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Star-Delta or Soft-Start for Large Fans<\/div>\n

Cooling tower fan motors above 11 kW should use star-delta starting or a soft-starter to reduce the starting current impact on the supply. The high fan inertia means the motor accelerates slowly under star-delta and the time in star connection is long \u2014 8 to 15 seconds is typical for a 6-pole motor driving a 4 to 6 m fan. The star-delta transition must be smooth; a resistor-assisted transition is preferred for large fans to avoid the current surge at the moment of delta connection.<\/p>\n<\/div>\n

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Two-Speed YD Motor for Seasonal Control<\/div>\n

Using a YD multi-speed pole-changing motor (4\/6-pole giving 1,450\/960 rpm) on the cooling tower fan provides two fixed fan speeds without a VFD. In summer peak cooling demand, the fan runs at high speed (1,450 rpm, maximum airflow and cooling capacity). In mild weather, switching to low speed (960 rpm) reduces fan power by approximately 70% (cube of speed ratio: (960\/1,450)\u00b3 = 0.29) while maintaining sufficient cooling. Two-speed control is the most cost-effective capacity control method for cooling towers that do not require continuous modulation.<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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6. Korea Ever-Power Y2 Series for Cooling Tower Fan Drives<\/h2>\n
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The Korea Ever-Power Y2 series in 6-pole and 8-pole configurations covers the 0.75 to 45 kW power range required for direct-drive cooling tower fan motors. The 6-pole Y2 at 960 rpm is the standard specification for the majority of industrial and commercial cooling tower fan applications. Korea Ever-Power supplies the Y2 for cooling tower service with enhanced moisture-resistant winding impregnation, corrosion-resistant exterior coating, and stainless steel terminal box fixings as a cooling tower package specification. The complete Y2 range is in the three-phase motor product section<\/a>. Contact Korea Ever-Power<\/a> for cooling tower package specifications including space heater, space heater control relay, and anti-condensation winding treatment options.<\/p>\n<\/div>\n

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Y2 \u2014 Cooling Tower Fan Specification<\/div>\n\n\n\n\n\n\n\n\n\n\n
Poles<\/td>\n6P (960 rpm) standard<\/td>\n<\/tr>\n
Power range<\/td>\n0.75\u201345 kW<\/td>\n<\/tr>\n
IP rating<\/td>\nIP55 standard<\/td>\n<\/tr>\n
Insulation<\/td>\nClass F, moisture-resistant<\/td>\n<\/tr>\n
Efficiency<\/td>\nIE3 (energy class)<\/td>\n<\/tr>\n
Duty<\/td>\nS1 continuous<\/td>\n<\/tr>\n
Space heater<\/td>\nOptional (100 W for CT service)<\/td>\n<\/tr>\n
Two-speed option<\/td>\nYD 4\/6-pole available<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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7. Cooling Tower Fan Drive Applications<\/h2>\n
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Industrial Process Cooling Tower<\/div>\n

Counterflow and crossflow cooling towers for industrial process cooling (chemical, petrochemical, power plant, manufacturing). Fan motors 7.5 to 45 kW, 6-pole, IP55, Class F. Typical tower cell configurations use 2 to 8 fan cells each with one motor. Y2 6-pole direct drive is the standard specification for cells with 2 to 5 m fan diameter.<\/p>\n<\/div>\n

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HVAC Building Cooling Tower<\/div>\n

Packaged and field-erected cooling towers for building air-conditioning chiller condensers. Fan motors 0.75 to 15 kW, 6-pole or 4-pole with gearbox for small towers. Two-speed YD motor popular for office building cooling towers where part-load operation is the majority of annual hours.<\/p>\n<\/div>\n

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Data Centre Cooling<\/div>\n

Cooling towers for data centre chiller plant condensing. Very high annual operating hours (8,760 hours\/year continuous). Y2 6-pole 3.0 to 22 kW, IP55, with space heater for the tower shutdown periods. Long life specification essential given the critical role of cooling in data centre continuity.<\/p>\n<\/div>\n

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Evaporative Condenser Fan<\/div>\n

Evaporative condensers for refrigeration systems (cold stores, food processing, industrial refrigeration) use a combined direct-air and evaporative cooling mechanism. Motor requirements are identical to cooling tower fan motors \u2014 IP55, 6-pole, moisture-resistant winding, corrosion-resistant exterior. Y2 0.75 to 7.5 kW covers most evaporative condenser fan applications.<\/p>\n<\/div>\n<\/div>\n

\n
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\"Y2<\/p>\n

Cooling Tower Fan<\/div>\n<\/div>\n
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\"Korea<\/p>\n

IP55 Water Jet Test<\/div>\n<\/div>\n
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\"Korea<\/p>\n

CE and ISO<\/div>\n<\/div>\n
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\"Korea<\/p>\n

Global Customers<\/div>\n<\/div>\n<\/div>\n<\/div>\n

<\/p>\n

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8. Frequently Asked Questions<\/h2>\n
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Our cooling tower fan motor failed after 18 months. How can we extend motor life?<\/div>\n<\/div>\n
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18-month motor life in a cooling tower is characteristic of a motor without adequate moisture resistance in the winding or adequate corrosion protection on external components. To extend life to the 8 to 15 year range typical of correctly specified cooling tower motors: (1) Specify IP55 minimum \u2014 IP54 is not adequate for the water droplet environment at the fan position. (2) Specify moisture-resistant winding impregnation \u2014 Korea Ever-Power Y2 cooling tower package includes an additional epoxy winding dip over the standard polyester varnish. (3) Add anti-condensation space heaters (100 W) with automatic control to energise when the motor is stopped \u2014 this prevents moisture accumulation in the winding cavity during the tower off-cycle. (4) Check and re-tighten terminal box lid fasteners and conduit glands at the first and third maintenance intervals \u2014 the vibration of the cooling tower structure can loosen these over time, allowing humid air to enter the terminal box and track across the cable terminations. (5) Apply touch-up paint to any areas where the cooling tower corrosive environment has attacked the motor exterior after the first year of service.<\/p>\n<\/div>\n<\/div>\n

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Can I use a VFD on a cooling tower fan motor to modulate cooling capacity continuously?<\/div>\n<\/div>\n
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Yes \u2014 and for cooling towers with high annual operating hours and significant load variation, a VFD on the cooling tower fan motor is one of the highest-return energy investments. The cubic law savings apply: reducing fan speed by 20% saves 49% of fan power. For the Y2 motor on a cooling tower VFD drive, specify the YVF2 inverter-duty motor with IC416 forced cooling, because the Y2 with IC411 shaft-mounted fan loses cooling airflow proportional to speed cubed \u2014 at 50% fan speed, the IC411 cooling drops to 12.5% while the motor still handles the same torque. The YVF2 with IC416 maintains full cooling at any speed. Also confirm that the VFD itself is housed in a sealed enclosure (IP54 or better) outside the cooling tower wet air zone \u2014 a VFD installed inside the cooling tower structure in the air path will be damaged by moisture ingress within weeks regardless of its IP rating.<\/p>\n<\/div>\n<\/div>\n

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The fan motor operates in reverse when the tower is shut down in winter. Is this damaging?<\/div>\n<\/div>\n
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Some cooling towers experience natural convection-driven reverse airflow through the tower when the fan is stopped \u2014 warm air from the basin rises naturally, creating an upward draft that spins the fan blades in reverse. This reverse windmilling is not mechanically damaging to the motor or fan if the reverse speed is below the forward rated speed, because the motor is simply rotating freely without electrical loading. However, if the reverse windmilling speed approaches or exceeds the motor rated speed, the motor acts as an induction generator and the voltage generated in the winding can cause voltage spikes that damage winding insulation. If significant reverse windmilling is observed (above approximately 50% of rated speed), add a damper to the tower fan outlet or inlet that closes when the fan is stopped to prevent natural convection reverse flow. Do not add a motor brake to prevent reverse windmilling \u2014 the motor is not designed for braking at high reverse speed and brake wear would be severe.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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Korea Ever-Power \u00b7 Y2 Series \u00b7 6-Pole Cooling Tower Fan Motor<\/div>\n

Need a Long-Life Motor for Your Cooling Tower?<\/h2>\n

Korea Ever-Power Y2 6-pole: IE3, IP55, Class F moisture-resistant, 0.75\u201345 kW. Corrosion-resistant cooling tower package with space heater option and epoxy winding treatment available.<\/p>\n

View Y2 Motor Range<\/a><\/p>\n<\/div>\n<\/div>\n

Edited by Cxm<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

Korea Ever-Power \u00b7 Y2 Series \u00b7 Cooling Tower Fan Drive Guide Electric Motor for Cooling Tower Fan Drives: IP55, High Humidity and Corrosion-Resistant Selection Cooling tower fan motors operate in the most severe long-term corrosion environment of any industrial motor application: continuous exposure to warm humid air saturated with water droplets, mineral deposits from evaporating […]<\/p>","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[28],"tags":[],"class_list":["post-236","post","type-post","status-publish","format-standard","hentry","category-industrial-electric-motor"],"_links":{"self":[{"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/posts\/236","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/comments?post=236"}],"version-history":[{"count":1,"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/posts\/236\/revisions"}],"predecessor-version":[{"id":239,"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/posts\/236\/revisions\/239"}],"wp:attachment":[{"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/media?parent=236"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/categories?post=236"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/industrialelectricmotor.net\/fr\/wp-json\/wp\/v2\/tags?post=236"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}