SCHURTER Application Note: Primary Protection Lighting0 pages

Application Note

Primary Protection Lighting
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SCHURTER SMD fuses for LED
technology
LED technology has totally revolutionized the lighting market. These devices bring
countless advantages, but their sensitive electronic circuits require suitable protection.
SCHURTER offers the optimal solution for every need.
Compared to other sources of lighting, LEDs
offer clear advantages: They consume up to 90
percent
less
energy
than
standard
incandescent bulbs. Their service life can
extend as long as 50,000 hours. They achieve
100 percent luminosity immediately after being
turned on, and total failures are practically
unheard of. Due to their small dimensions they
also save space, and thanks to a wide selection
of colors they are very versatile in terms of
applications.
In most cases, the service life of the LEDs
exceeds that of the entire lighting fixture.
Because there is no expectation of replacing
LEDs as is the case with incandescent bulbs,
they can be affixed permanently to the lighting
fixture. To power the LEDs, an electronic circuit
connects to the AC power grid and generates
a stable, controlled DC voltage. In case of a
malfunction, though, it is possible for high
currents to arise which can be hazardous to
people and possibly start a fire.
The requirements on the primary protection of
LED lighting systems are very high. The
simplest and most reliable way to achieve
primary protection is with a midget fuse. Such
fuses require a sufficiently high I2t value to
ensure they are not tripped by inrush current
peaks. They also require high breaking
capacity so they can, for example, interrupt the
current path in case of a short circuit. Further, a
compact design is important because power
supplies for LEDs are kept very compact.
Finally, fuses for the primary protection of LED
lamps must guarantee reliable protection over
long operating periods and at high
temperatures.
SCHURTER fulfills these exact requirements
in an optimal way with the UMT 250, UMF 250
and UMT-H SMD fuses. They are very robust
in handling high inrush current peaks thanks to
their time-lag and quick-acting characteristics,
a high I2t value and high breaking capacity of
up to 200 A for the UMT 250/UMF 250 and
1500 A for the UMT-H.

The compact dimensions of 5.3x16 mm for the
UMT-H and 3x10.1 mm for the UMT 250 and
UMF 250 make it possible to use the SMD
fuses even in devices where space is very
limited. Reliable tripping over a large
temperature range during their entire service
life, a low voltage drop and an attractive price/
performance ratio make the UMT-H,
UMT 250 and UMF 250 excellent choices
wherever quality and reliability are in high
demand.

Technical features UMT 250 and
UMF 250:

Technical features UMT-H:
-t
-t
-t
-t
-t
---

High rated voltages up to 250-277 VAC t
and 250 VDC
High breaking capacity (H) of 1500 A at t
rated voltage
19 rated currents from 160 mA
to 10 A
Time-lag (T) characteristics according to t
UL 248-14
Compact, square design, easy PCB as-t
sembly and soldering
Halogen-free and RoHS-compliant
cURus approval

-- Rated voltage of 250-277 VAC and
t 125 VDC
-- High breaking capacity up to 200 A
-- 34 rated currents from 50 mA up to 10 A
-- Quick-acting (F) characteristics
-- Compact, square design, easy PCB as-t
t sembly and soldering
-- Halogen-free and RoHs compliant
-- All global main approvals such as VDE,
tcURus

UMT-H, a compact SMD fuse when high
breaking capacity is required (source:
SCHURTER)

Close to the customer

UMT 250 compact SMD fuse for primary
protection of LED lighting systems
(source: SCHURTER)

Circuit Protection

SCHURTER is your expert partner when it
comes to circuit protection. SCHURTER supports its customers with extensive knowledge.
And in cases where standard products are not
exactly what you need, SCHURTER is happy to
work out a customized solution.

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