Raintight vs Dripproof?

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iwire

iwire

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I had to order a small motor and I noticed that my choices where between an Open Dripproof Motor and Totally Enclosed Fan Cooled Motor.

Are either of these OK outdoors? :)
 
Re: Raintight vs Dripproof?

According to ye ol Hoffman catalog (I assume these would apply to motors as well as enclosures):

Drip-tight:

Constructed so that falling moisture or dirt does not enter the enclosure under specified test conditions. Type 3, 4, 4x, 12, 12K, and 13 enclosures meet this requirement.

Outdoor:

Constructed or protected so that exposure to the weather will not interfere with successful operation of equipment. Type 3, 3R, 4, 4X, and 6 enclosures meet this requirement.

Notice that types 12 and 13 are drip-tight, but not Outdoor. I think outdoor enclosures have to be protected from blowing rain and snow, and drip-tight does not meet this requirement.

By the way, there is lots of good info in the "Standards" appendix to the hoffman catalog.
 
Re: Raintight vs Dripproof?

From Grainger catalog (lots of good info in there!!)

Open Dripproof (ODP) Ventilation openings in endshields and shell placed so drops of liquid falling within an angle of 15 degrees from vertical will not affect Performance. Usually used indoors, in fairly clean locations.

Totally Enclosed Fan Cooled (TEFC) includes an external fan in a protective shroud, to blow colling air over the motor, but not airtight or waterproof.

Totally Enclosed Nonventilated (TENV) not equipped with an external cooling fan, but not airtight or water-proof. Depends on convection air for cooling.

Washdown - Designed for use in wet areas, or applications that require frequent cleaning.

Hope that helps.
 
Re: Raintight vs Dripproof?

i wire.I spent many years in the electric motor business and I would never apply an open dripproof motor outside. They are nowhere close to as good at shedding rain as a 3r enclosure. I have rewound lots of odp motors which were misapplied outdoors and had blown to ground in the slots due to moisture and subsequent breakdown of the slot cell insulation. If the customer insisted upon using the rewound unit in the same area we would use an epoxy encapsulation method to protect the winding but would also include a warranty disclaimer. I have always reccomended using TEFC motors otside but as you say I have also seen odp units work for a long time outside without failing as well. The real consideration is cost as well as proper application. TEFC motors generally cost about 30% more than a comparable odp.You may also want to load up NEMA MG2. It gives you the exact description of both plus a lot more real good info.

[ June 09, 2004, 03:14 PM: Message edited by: stew ]
 
Re: Raintight vs Dripproof?

Thanks Stew I was hoping you would see that question I knew you had motor experience. :)

I kinda figured that a drip proof was really not good for outside even if they do sometimes end up there.

I once got to watch 'lightning' jump out of a 200 HP DC motor that someone insisted on trying out while soaked inside with water.

The shame of it was the unit had a seperate AC cooling fan that would have dried it out and we could have waited a few days for it to dry before trying out the DC motor.

We had to wait much longer while a motor shop fixed it. :D

Bob
 
Re: Raintight vs Dripproof?

Its always exciting to see or hear a grounded stator go bang. Dangerous as well. We eliminated the fireworks in our shop however when I purchased a Step voltage testing unit. It was and autotransformer with taps at 30/60 120/208/220/240/460/480 volts 3 phase. Worked real well on units that mite test ok with a megger but had turn to turn failures or coil to coil shorts. You started the unit on 30 volts and observed the 3 ammeters. Then shut of and went to 60 volts etc until you had whatever the full voltage was. At 30 or 60 volts a turn to turn failure wowuld appear as unballanced current and would only sound like bacon frying. Took all the excitement and fireworks out of it tho!!!

[ June 09, 2004, 03:58 PM: Message edited by: stew ]
 
Re: Raintight vs Dripproof?

NEMA MG-2 Safety Standard and Guide for Selection, Installation, and Use of Electric Motors and Generators

...
4.1 Open Machine (IP00, IC01)
An open machine is one having ventilating openings which permit passage of external cooling air over and around the windings of the machine. The term ?open machine,? when applied in large apparatus without qualification, designates a machine having no restriction to ventilation other than that necessitated by mechanical construction.
4.1.1 Dripproof Machine (IP12, IC01)
A dripproof machine is an open machine in which the ventilating openings are so constructed that successful operation is not interfered with when drops of liquid or solid particles strike or enter the enclosure at any angle from 0 to 15 degrees downward from the vertical.
The machine is protected against solid objects greater than 2 inches.

...

4.2 Totally Enclosed Machine
A totally enclosed machine is so enclosed as to prevent the free exchange of air between the inside and outside of the case but not sufficiently enclosed to be termed air-tight and in which dust does not enter in sufficient quantity to interfere with satisfactory operation of the machine.
4.2.1 Totally Enclosed Nonventilated Machine (IC410)
A totally enclosed nonventilated machine is a frame-surface cooled totally enclosed machine which is only equipped for cooling by free convection.
4.2.2 Totally Enclosed Fan-Cooled Machine
A totally enclosed fan-cooled machine is a frame-surface cooled totally enclosed machine equipped for self exterior cooling by means of a fan or fans integral with the machine but external to the enclosing parts.

...
Click to expand...
NEMA MG-2 is available as a free download at:

http://www.nema.org/help/docno.html#M
 
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