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LOCC Box DC Electronic fuse

  • Reliably trips 24 V DC circuits
  • Adjustable between 1-10 A
  • Can be supplied via distribution rail
  • Selectable characteristic
  • Remotely Resetable

Miniature circuit breakers connected to 24 V DC often have difficulty in tripping, especially with long cable runs and small cable areas. Selectivity does not work and all groups drop out before the miniature circuit breaker trips in the thermal range, which can take several minutes.

Lutze's LOCC Box range of electronic fuse trips reliably even with long cable runs, which provides good selectivity without power outages for fault-free groups. The fuse's rated current is set using a thumb-wheel under the safety cover. The current can be set between 1-10 A in 1 A steps.


NB: Change to rated current and characteristic can only be made when the fuse is in the disconnected position. LED turns red. If the rated current or characteristic is changed during operation, LED turns green so no change occurs. To change settings. Press the button at the front until the LED turns red (non-flashing). Change the value on the thumb-wheel and then restart using the button on the front.

Three different characteristics can be selected using a thumb-wheel:


  • 1 : Fast blow,
  • 2 : medium blow,
  • 3 : slow blow,
  • 4 : slow blow 2,
  • 5 : slow blow 3.


Use the slow blow characteristics for connection of loads with high inrush current. Even if the slowest ranges are chosen, the fuse reacts very quickly to short circuits compared to miniature circuit breakers., that are only really designed for AC loads.

The 24 V DC connection can either be made directly to each fuse or using a power terminal block with a copper rail. This alternative is recommended if many fuses are to be installed beside one another. The fuse is connected to the rail using a sliding contact. Upon disconnection of the sliding contact, the fuse is galvanically isolated.


Resetting can either be conducted with a button on the front (the fuse can also be manually disconnected with the button) or via remote control. In the event of a tripped fuse, the LED flashes red. Once a fault is remedied, the fault is acknowledged with the button on the front or via remote control. The LED is then red, non- flashing. If many fuses are installed, it is easy to see which groups have been remedied. With a second reset signal, the fuse is activated and the LED shines green.


There is also a 24 V DC signal output (open collector) that falls when the fuse trips. The output can be connected into a group using strapping. If one of the fuses in the group trips, a signal is received. On model 716401, the signal output even falls with manual on and off.
(For more information about the lowest load resistances for the signal output, see the separate tab.)

The cover can be locked with a lead seal and marked with our RC55 marking; see the terminal rail chapter. The fuse has no galvanic isolation between input and output when it is connected to 24 V DC.


The LOCC Box is also available as a network version and can be combined with exsiting systems, operating with RS-232, CANopen, Profibus DP, Profinet IO or Ethercat protocols.


LOCC-Pads is free software that can be used with the LOCC Box-NET for programming your own parameters to match the load you are protecting,as well as a full anaysis & diagnostic tool for 12-24V dc circuits.


Please contact for a demostration.





Terminal voltage

12/24 V DC

Max. voltage range

10-32 V DC

Max. input current

10 A

Max. current via distribution rail

40 A DC copper rail 10x3 mm

Remote control


Signal level

24 V DC (EN 61131)

Pulse time for shut-off via remote control

>100 ms <800 ms

Pulse time for reset via remote control

>1 s




Output semi-conductor


Max. output current

10 A DC

Selectable current ranges

1-10 A. in 1 A steps

Memory for power failure

Yes, the fuse remembers status and resets to this position when the power returns.

Voltage drop over the semi-conductor

<170 mV at 10 A

Max. capacitance

10,000 µF

Status indication

LED. Constant green: OK; Flashing: 90 % load. Flashing red: tripped fuse


1: Fast blow, 2: medium blow, 3: slow blow, 4: slow blow 2, 5: slow blow 3. See diagram.


Signal output*


Output signal 24 V DC

Connection OK, no short circuit/overload detected

Output signal 0 V DC

Fault in circuit, output disconnected. 716401: Drops to zero even with manual shut-off

Output component

Transistor, open collector. Max 2 A


General data



DIN rail


Spring 0.25-2.5 mm²

Operating temperature

-25 °C to +50 °C

IP class


Possible installation angles



120 g

Dimensions HxDxW

114.5x116x8.1 mm


PA 6.6 (UL94-0;NFF 12, F2)



Complies with standards

EN 60950-1; EN6131-2,2; EN 60947-4-1


EN55022, EN61000-6-3, EN61000-6-2



The signal output is of the open-collector type with pull-up resistors. With this design, groups can be combined and alarms triggered if one fuse in the group trips. Depending on the external load resistance, the output voltage for a non-tripped fuse can vary.
Example 1 . Only one fuse is used; the alarm output is connected to a PLC input of 10 kΩ. The output signal of the alarm output during operating status is 19.8 V DC. The alarm output's internal resistance is 2.1 kΩ. Re/Rtot * U = 10 kΩ/12.1 kΩ * 24 = 19.8 V)
Example 2 : 10 fuses are connected together into a group with a common alarm output to a PLC input of 10 kΩ. The output signal of the alarm output during operating status is 23.5 V DC. The alarm output's internal resistance is 2.1 kΩ. 2.1 kΩ/10 = 210 Ω. Re/Rtot * U = 10 kΩ/10.21 kΩ * 24 = 23.5 V DC.

If a relay coil that is often of low resistance is to be connected directly to the alarm output, +24 V DC must be connected directly to the relay; minus must be connected to the alarm output. NB: An inverted function is attained. When the fuse does not indicate a fault, the relay is not activated; relay activation occurs when there is a fault. We recommend our interface relays from Lutze, which have the same form factor as the fuse.
Plug-in interface relays for outputs

If the MOSFET transistor that feeds the loads fails for some reason during operation, the signal output will drop to zero. LED at the front will flash at very high rate and indicate a MOSFET transistor fault. If a short circuit occurs in conjunction with a MOSFET transistor fault, an internal fuse trips and disconnects the loads. With these integrated safety functions, a very safe system is attained even in the event of electronics failure.






1: Output

2: External reset/shut-off

3: Status output

4: Not connected

5: 0 V

6: 24 V DC (single supply)

7: 24 V DC supply via rail



Fast blow (no 1)

Medium blow (no 2)

Slow blow 1 (no 3)

Slow blow 2 (no 4)


Slow blow 3 (no 5)




There are many accessories available for the fuse that simplify the installation.

Power terminal block with end plate

Power terminal block for busbar

Minus terminal block

Supplies the copper rail with 24 V DC.
A contact slot is pushed onto
the rail and the connection is complete.
Up to 6 mm² cable can be
connected. The desired number of
fuses are connected to the
rail and connected with the end plate.
The terminal blocks build for a total of 20 mm

The terminal block is used with
the standard power terminal block to
the left to obtain dual
power supply connections to
the copper rail

The minus terminal block
has the same physical
execution as the fuse
and can also be connected to a rail. Each
minus terminal block has 6 outputs that
can be connected to a load. (5 if feed
is not via the rail). If both the fuse
and the minus terminal block
are separated from
the respective rails, full
isolation is attained from the
load, which enables isolation measurement.

Empty casing


Jumper bars

Enables full physical expansion
and correct length of the
copper rail. Example: If construction
is to be in steps, this makes the
application future-safe. The empty casing
is lifted away and
replaced with a “live” fuse as
needs arise.

Used as isolation of the
end of the fuse if the distribution
terminal block is not used.
The connection for the copper
rail is not isolated on the left side.
The spacer can also be used
to create an air gap between the

Available in 3 colours: white, red and blue.
8 or 16 poles
Used for example to link together
the minus connection to
the feed and to connect together
the fuses’
alarm outputs.

The power terminal block provides a flexible solution for many different purposes. Below are some mounting alternatives .


For redundant connection of
power supply.

It the heat decreases from the
connection rail, the feed is
partially executed at the middle of the rail.

For further connection of 24 V DC
to a new terminal block with fuse.


A power terminal block manages 40 A. The 70 A rail. With connection of two power terminal blocks,
the entire rail's capacity of 70 A can be utilised.




Order no.


Supply voltage


LOCC Box Electronic fuse, 1-10 A, Adjustable

12 - 24 V dc


LOCC Box Electronic fuse, 1-10 A. Adjustable, Alarm output controlled by button

12 - 24 V dc


LOCC Box Electronic fuse, 1-6 A. Adjustable, Alarm output controlled by button

48 V dc


LOCC Box- EC, Electronic fuse, fixed charateristics, Alarm output controlled by button

12 - 24 V dc


LOCC Box-SC, Electronic fuse for protecting safety relay contacts, 1-5 A. Adjustable, Alarm output controlled by button

12 - 24 V dc


LOCC Box,  Electronic fuse, 0.2-2A. Adjustable, Alarm output controlled by button

12 - 24 V dc


LOCC Box-NET Electronic fuse with communications, 1-10 A. Adjustable , Alarm output controlled by button


12 - 24 V dc


LOCC Box-C2,  Electronic fuse for providing Class 2 circuits, 0.5-4A. Adjustable, Alarm output controlled by button







Gateway Communication Module for 716410 - USB, EtherCAT

12 - 24 V dc


Gateway Communication Module for 716410 - USB, PROFINET IO

12 - 24 V dc


Gateway Communication Module for 716410 - USB, PROFIBUS-DP

12 - 24 V dc


Gateway Communication Module for 716410 - USB, RS-232 & CANopen

12 - 24 V dc





Power terminal block for electronic fuses. Max. 40 A (power block + end block) 10mm² cable



Power terminal block for electronic fuses. Max. 40 A (power block + end block)  16mm² cable



Power terminal block for passage of copper rail. Max. 40 A



Copper rail 1 m. 10x3 mm. Max. 70 A



Tamper protection for copper rail



Minus terminal block with 6 outputs



Empty casing



Spacer/isolation terminal block






Jumper bar, 16-pole, White, 6 A



Jumper bar, 16-pole, Red, 6 A



Jumper bar, 16-pole, Blue, 6 A



Jumper bar, 8-pole, White, 6 A



Jumper bar, 8-pole, Red, 6 A



Jumper bar, 8-pole, Blue, 6 A



Jumper bar, 8-pole, White, 16 A



Jumper bar, 8-pole, Red, 16 A



Jumper bar, 8-pole, Blue, 16 A