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LAD6K / LA6DK latch block limitations of use

The LAD6K10* / LA6DK20* latch block that attaches to the TeSys D series contactors and control relays enables mechanical latching.

Due to the design of the coil in the latch block, there are a number of precautions to be observed when using these devices. In addition, where the previous 'D2' version of the contactor and the previous generation of LA6DK block are replaced with the TeSys D versions there are some important differences to consider.

Precautions to observe when using the LAD6K10* / LA6DK20* latch block (also refer to the user manual attachment).

  • Never energise the contactor / relay coil and the latch block coil at the same time.
  • Minimum pulse time required to unlatch the contactor:
    100 ms with ac coil
    250 ms with dc coil
  • Maximum pulse time: 10 seconds
  • maximum operating rate: 1200 cycles/hour
Important differences between the original LA6DK1* , LA6KDK2* and LA6DK3* used on the 'D2' series and the current TeSys D series LAD6K10* / LA6DK20*

There are important differences between the new latch block and the original 'D2' type;
  • The new latch block does not incorporate an auto cut out of the un-latch coil within the latch block. Thus, it is important to ensure the circuit controlling the energisation of the de-latch coil confirms to the precautions detailed above.
  • LA6KDK2* and LA6DK3* were also fitted with a N/C contact that could be used as a 'cut throat' for the coil circuit of the host D2 contactor. This feature is not included on the TeSys D latch blocks.
*Coil code letter.
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