Schneider Electric LADN31 TeSys D 3 NO + 1 NC Contact Block

LADN31: three NO and one NC contacts in a four-contact TeSys D block

The LADN31 is a Schneider Electric TeSys D front auxiliary contact block with three normally open and one normally closed contact. It is for contactors that report to several systems and need only one interlock. Seven Star LLC supplies the LADN31 in Oman and the GCC as an independent supplier based in Muscat.

The 31 reads three NO, one NC. The datasheet lists protection as IP2X where the other group members state IP20; the practical meaning is the same, finger-safe terminals, but the wording is worth noting when specifying.

Technical specifications of the LADN31

Ordering the LADN31

• 3 NO + 1 NC contact pattern.
• Family compatibility as listed for LADN contact blocks.
• 44 mm width to be free on the contactor front.
• Check where the single NC contact is used for interlocking.
• Alternative patterns: LADN22 and LADN40.

When 3 NO + 1 NC on the LADN31 fits the scheme

Count the signals the contactor has to give: one self-hold, one lamp, one PLC input, and one interlock. That is three closing contacts and one opening contact, exactly the LADN31 pattern.

Where a second interlock is needed, move up to a LADN22 and give up one of the closing contacts.

Ratings and compatibility of the LADN31

Rated operational voltage is 690 V AC at 25 to 400 Hz, with conventional thermal current of 10 A at 60 °C. Rated operational current is 6 A at 120 V AC-15, 1.04 A at 690 V AC-15, 0.55 A at 125 V DC-13 and 0.1 A at 600 V DC-13. Making capacity is 140 A AC and 250 A DC, protection is a 10 A gG fuse, mechanical durability is 30 Mcycles, and the minimum switching level is 5 mA at 17 V. The non-overlap time between the NC and NO contacts is 1.5 ms on energisation and on de-energisation.

The block is 44 mm wide, 48 mm high and 42 mm deep and mounts on TeSys D and TeSys F contactors as listed in the datasheet. Environmental limits are -5 to 60 °C and 3000 m.

LADN31 uses in Oman and the GCC

Process pumps, compressor starters and crane drives have status, alarm and permissive signals taken from the main contactor. The three closing contacts go to the PLC, a local lamp and a remote indication, while the opening contact interlocks the opposite direction.

In hot panel rooms, keep the block clear of heat sources and ventilated.

LADN family: the LADN31 compared with its siblings

All six references below are front-mounting TeSys D blocks with screw clamp terminals; they differ in contact pattern and width.

LADN31 installation and test

Seat the block on the front, tighten each terminal at 1.7 N.m and test the four contacts under both states of the contactor.

Add a clear label on the cabinet door drawing for the single NC contact, since a three-to-one split is easy to misread.

Information to send with an RFQ for the LADN31

• Full reference and quantity required
• Contactor model the block mounts on
• Contact arrangement needed (NO and NC count)
• Control voltage and load of each circuit
• Delivery location and timing

Storage, handling and spares for the LADN31

Keep the LADN31 in its original packaging in a dry, dust-free store until installation, and check the label against the order before fitting. For plants that run continuously, holding one spare unit on site shortens downtime if a replacement is needed during a shutdown or after a fault. Record the reference and installation date in the maintenance log so the next order can be placed quickly.

Documents and quotation

A datasheet for the LADN31 is attached on this page. It carries the electrical, mechanical and environmental data summarised above, so the figures can be checked against your drawings.

Send the part number, quantity and application and we will confirm availability and a quotation. Seven Star LLC is an independent supplier in Muscat and is not affiliated with the manufacturer.