Siemens BETA Low-Voltage Circuit Protection

BETA Protecting

Low-Voltage Fuse Systems

NP LV HRC fuse switch disconnectors

3/90

Siemens ET B1 · 10/2008

You can order this quantity or a multiple thereof.

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SENTRON 3NP fuse switch disconnectors

NP40 10

NP40 70

NP52 with opened fuse carrier

The SENTRON 3NP4 and 3NP5 fuse switch disconnectors are

climate-proof and meet the requirements of IEC 60947-1,

IEC 60947-3 and DIN VDE 0660-107.

For use in heavily sulfurous atmospheres, the SENTRON 3NP5

series and the 3NP40 1 and 3NP40 7 versions are available as

tinned modules (delivery on request). The SENTRON 3NP5 fuse

switch disconnector series also complies with the standard

BS 5419 and is approved for use in shipboard systems

(

use approved fuse links).

All SENTRON 3NP4 and 3NP5 fuse switch disconnectors can be

sealed as standard or can be sealed through accessories.

Fuse monitoring by SIRIUS motor starter protector

For fuse monitoring, a SIRIUS motor starter protector is factory-

fitted and hard-wired to the fuse carrier of the SENTRON 3NP4

and 3NP5 fuse switch disconnectors. If the fuse carrier is closed,

the three conducting paths of the SIRIUS motor starter protector

are switched in parallel to the fuse links to be monitored. If the

fuse carrier is open, all main current paths of the motor starter

protector are off circuit. The internal resistance of the motor

starter protector is great enough not to impair the protective

function of the monitored fuse links. Failure of a fuse will trip the

motor starter protector.

Electronic fuse monitoring EF

For electronic fuse monitoring, the EF monitor is factory-fitted

and hard-wired to the fuse carrier of SENTRON 3NP5 fuse switch

disconnectors.

The EF monitor works independently of any loads. Failure of a

fuse can be relayed to a control room through integrated auxiliary

switches (2 NO + 1 NC) by means of a centralized fault indica-

tion or used to isolate the load through e.g. a contactor.

Actuation of the auxiliary switch depends on the EF version.

Version "A" stands for "open-circuit principle", version "R" for

closed-circuit principle"

(

see block diagram)

If a fuse is tripped, a green LED signal flashes (general fault) and

the location of the failed fuse is indicated by a red LED. Using

more than one device facilitates identification of the affected

branch circuit. The EF monitor is automatically reset to the

standby position once the faulty fuses are replaced. This state is

indicated visually by the status display (green LED). The EF

monitor is also suitable for use in industrial systems badly

afflicted by harmonics.

Auxiliary switches

The SENTRON 3NP4 and 3NP5 fuse switch disconnectors can

also be retrofitted with auxiliary switches for indicating the

switching position of the fuse carrier. One switch block (1 CO)

can be mounted on SENTRON 3NP4 fuse switch disconnectors

size LV HRC 000 and two switch blocks (1 CO) on sizes LV

HRC 00 to LV HRC 3 respectively. SENTRON 3NP5 fuse switch

disconnectors can also be delivered with a 2-pole auxiliary

switch (1 NO + 1 NC) if required. The version with fuse monitor-

ing is fitted with this auxiliary switch as standard.

The auxiliary switch of the motor starter protector can be used for

indication purposes or to disconnect the main circuit, e.g. through

a contactor. The signal lead for the SENTRON 3NP4 fuse switch

disconnector size LV HRC 00 needs to be ordered separately.

Sizes LV HRC 1 to LV HRC 3 are connected using flat terminations.

Delivery of the SENTRON 3NP5 fuse switch disconnectors includes

the signal lead, complete with connector. SIRIUS motor starter pro-

tectors cannot be used for fuse monitoring in branch circuits by

motor starter protectors where a fault may result in > 220 V DC

feedback. In the case of parallel cables and meshed networks,

only a voltage difference of > 24 V at the switch will trigger the

motor starter protector.