What is the function of this connection ?

Discussion in 'General Electronics Chat' started by Externet, Aug 11, 2016.

  1. Externet

    Thread Starter AAC Fanatic!

    Nov 29, 2005
    758
    57
    Hi.
    This fan motor at the bottom works on 240VAC into its purple and black wires. Its red wire is for slow speed, not used, and shown connected to a 'parking' terminal just to prevent from being loose around. Ignore its red wire as there is no connection.

    There is a wire between M1 and a normally closed contact of a relay at bottom. What is it for, how does it work ?

    P1010623.JPG
    Or, if you prefer the original, is on page 6 ----> http://www.alpinehomeair.com/related/ARPF Spec1.PDF
    with the second 2-heater option installed.
     
  2. #12

    Expert

    Nov 30, 2010
    16,252
    6,749
    The M1 connection is a connection for the heater to be energized by L2. The connection from the heater sequencer at M1 to the N.C. forces the fan on any time the heater is on. It's a safety thing.

    If the switch at the bottom is in the N.O. position, the fan is always on. Therefore, the N.O. and N.C. function is controlled by the green wire from the thermostat and the delayed shut-off function of the "EBTDR". Just a long winded way to say, "persist running for a minute or so after the off command".

    These "persist after off" relays were invented just after the efficiency laws were passed because they suck the last drop of cooling out of the evaporator after the compressor shuts off.
     
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  3. Externet

    Thread Starter AAC Fanatic!

    Nov 29, 2005
    758
    57
    Thanks for your clear and accurate explanation, #12.

    As you are familiar with these animals... the sequencer takes -say 20 seconds- for its PTC heater to engage... 20 seconds to engage M1 to M2 and then other 20? seconds to engage M3 to M4 ; or both contact sets do it simultaneously ? There is only one PTC 'heater' inside the sequencer relay.
     
  4. #12

    Expert

    Nov 30, 2010
    16,252
    6,749
    If it's a, "stacked sequencer" the label on the top will say something like:
    M1-M2 H20-40 C 60-90
    M3-M4 H 60-100 C 15-30

    That means the M1-M2 contact comes on quick (20 to 40 seconds) (and brings the fan motor) and stops slowly (60 to 90 seconds after the heat command from the thermostat stops).
    The M2-M3 connection activates slower and disconnects quicker.
    This accomplishes two things. 1) The lights don't dim when 10KW of heat comes on in one click. 2) the M1 contact is in charge of starting the fan from first heat to the last of the sequence when all heaters are off.
     
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