TEFC Motor (Totally Enclosed Fan Cooled)
A TEFC motor is a totally enclosed electric motor whose frame surface is cooled by a fan mounted on the motor’s own shaft, so the cooling air never passes through the inside of the machine.
The name is two separate statements joined together. Totally enclosed describes the enclosure: there is no deliberate air path between the inside of the machine and the outside. Fan cooled describes how the heat leaves: a fan on the shaft blows ambient air over the outside of the frame.
Because the fan sits on the motor’s own shaft, the cooling is driven by the machine itself. That single fact explains almost everything a TEFC machine does well and everything it does badly.
Also written: TEFC · TEFC motor · totally enclosed fan cooled · totally enclosed fan cooled motor · TEFC enclosure
What the term fixes, and what it leaves open
| Full form | Totally Enclosed Fan Cooled |
|---|---|
| IEC / GB cooling code | IC411GB/T 1993—93, equivalent to IEC 34-6:1991 |
| What the first digit 4 means | Frame-surface cooled, using the surrounding mediumGB/T 1993—93, circuit-arrangement characteristic numeral |
| What the two 1s mean | Both circuits move by self-circulation — driven by the machine’s own rotationGB/T 1993—93, movement-of-coolant characteristic numeral |
| Air path through the windings | None. Internal air circulates inside; external air stays outside |
| Degree of protection (IP) | Not fixed by TEFC — IP is a separate code and a separate test |
| North American equivalent term | TEFC is itself the NEMA term; IC411 is the IEC way of saying it |
| Nearest codes that are not TEFC | IC410 (no fan) · IC416 (separately driven fan) · IC611 (air-to-air heat exchanger) |
Why the shaft-mounted fan is the whole story
A fan on the motor shaft turns at motor speed. At rated speed it moves the air the machine was designed around. At half speed it moves far less — and the losses inside the machine have not halved with it.
This is why a TEFC machine that is perfectly adequate on a fixed supply can overheat on a variable speed drive at low speed, and why variable-speed duty often calls for IC416 instead: same totally enclosed frame, but the fan is driven by its own small motor at constant speed regardless of what the main machine is doing.
It is also why a TEFC machine caked in dust or lagged with insulation gets hot. The frame surface is the heat exchanger. Anything covering it is reducing the cooling, not just looking untidy.
How to read the code instead of the acronym
The IC code is more precise than the acronym, and it is on the nameplate. In IC411, the 4 says the machine is cooled through its frame surface using the surrounding air. The two 1s say that both the internal and external coolant circuits are moved by self-circulation — that is, by the machine turning.
Change the last digit and you change the machine: IC416 means the external circuit is moved by a separately mounted component with its own drive. IC410 means free convection with no fan at all, which the NEMA world calls TENV.
What TEFC Motor does not tell you
TEFC is not explosion protection
A totally enclosed frame is not a flameproof enclosure and carries no Ex certification. Explosion protection is a separate construction, a separate standard and a separate certificate. In a Division 1 or Zone 1 area a TEFC machine is not sufficient on its own.
TEFC is not an IP rating
TEFC describes cooling; IP describes the ingress of solids and water. A TEFC machine can be IP54 or IP55 or IP65 — you have to read the IP code, not infer it from the word "enclosed".
"Totally enclosed" does not mean sealed
It means there is no intentional air exchange between inside and outside. It is not airtight, and it is not a hermetic seal. Machines still breathe through joints as they heat and cool, which is why drain plugs and anti-condensation heaters exist.
TEFC says nothing about duty or insulation class
How long the machine may run, and how hot the winding may get, come from the duty type and the thermal class. Two TEFC machines of the same frame can be rated very differently.
Which LEADGO series are TEFC
These series carry IC411 in their published cooling specification — that is, they are TEFC. Where two codes are shown, both cooling arrangements are offered on that series, so the code has to be stated on the order rather than assumed. The list is generated from the same parameter master data the product pages use, so it cannot drift away from them.
DYG Series
IC411
GTYP Series
IC416 / IC411 (air cooled)
TYC Series
IC411
TYP Series
IC411
YBX3
IC411
YBX4
IC411
YBX5
IC411
YD Series
IC411
YDGJ Series
IC411
YDT Series
IC411
YE3 (IE3)
IC411
YE3 Compact HV
IC411
YE3 Large-Power
IC411
YE4 (IE4)
IC411
YE4 Large-Power
IC411
YE5 (IE5)
IC411
YEJ Series
IC411
YFBX3
IC411
YFBX4
IC411
And which are deliberately not
These are totally enclosed too, but not fan cooled in the TEFC sense. Asking for "TEFC" on one of these would be asking for a different machine.
CYJTYP Series
IC410, totally enclosed natural cooling
DZTYP Series
IC410
GTYPS Series
Water cooled
TYPL Series
IC410
YBBP
IC416 (separately driven fan)
YBBPX3
IC416 (separately driven fan)
YFBBPX3
IC416 (separately driven fan)
YKK / YXKK
IC611 / IC616
YVP Series
IC416 (separately driven fan)
Frequently asked
What does TEFC stand for on a motor?
Totally Enclosed Fan Cooled. The frame has no deliberate air path between inside and outside, and a fan mounted on the motor’s own shaft blows ambient air over the outside of the frame to carry the heat away. In IEC terms the same construction is written as cooling code IC411.
Is a TEFC motor explosion proof?
No. A totally enclosed frame is not a flameproof enclosure, and TEFC carries no hazardous-area certification of any kind. Explosion protection is a separate construction with its own standard, its own certificate and its own marking on the nameplate. If the area is classified, the marking is what you check, not the enclosure description.
What is the difference between TEFC and TENV?
The fan. TEFC has a shaft-mounted fan blowing over the frame; TENV has no fan and relies on free convection from the frame surface, which is IC410 in IEC terms. TENV machines are quieter and have nothing to clog, but for the same frame they carry less output because they shed less heat.
Can a TEFC motor be used on a variable frequency drive?
It can, but the cooling has to be checked at the lowest speed the machine will actually run at, not at rated speed. The fan is on the motor shaft, so it slows down exactly when the machine still has losses to get rid of. Where a wide speed range is needed the usual answer is a separately driven fan — cooling code IC416 — which runs at full speed whatever the motor is doing.
Does TEFC tell me the IP rating?
No, and this is the most common misreading of the term. TEFC describes how the machine is cooled. IP describes how well it resists solid objects and water, and it is established by a separate test with its own two-digit code. A motor can be TEFC and IP54, or TEFC and IP65 — read the IP code on the nameplate.
Where this is worked through properly
What TEFC actually means →
the long version, including what it does not certify
Motor IP ratings explained →
the separate code TEFC is often confused with
Replacing a fan motor →
why cooling basis has to match, not just kW
Reading an Ex marking →
what a hazardous area actually requires
Motor duty types S1 to S10 →
the rating TEFC says nothing about