Maneurop Mtz81 internal overload

[Drew]

Hey all,
ive got an Mtz 81 maneurop compressor that's opening circuit just on one phase while running. The amps are initially fine (10.2 amps) on all three phases .after a minute or so the one phase stops drawing current, the other 2 climb to 18 amps. This could seem like I've lost a phase but I'm reading line voltage across all terminals at the compressor. I turn off the compressor and meter out the windings and only get continuity through 2windings and nothing through the one.Seconds later the winding returns and on starting the compressor the amps are fine for a bit again.

Firstly does the maneurop compressor internal overload open all windings when it trips? Because this compressor is opening one winding only.
secondly the compressor is showing no indications of high amps for the overload to react to? The compressor is also cool to the touch so I don't think it's tripping from heat?
while running the pressures look ok . could this be a faulty internal overload or am I missing something?

[RusBuka]

Stretch all contacts, test the contactor who starts the compressor.
Internal protection of the compressor disconnects a power at overloads, but on all phases, instead of on one.

[monkey spanners]

Sounds like the compressor klixon or windings are faulty but to check its no an external cause or issue swap the wires as below,

As connected now,

L1 - L1
L2 - L2
L3 - L3

Change to,

L1 - L3
L2 - L1
L3 - L2

The motor will still turn the same direction but you can see if the fault stays on the same winding or stays on the same incomming power connection.

[goshen]

Hi drew
if as stated your internal klixon opened then unfourtunatly your comp should be replaced ,
once the internal klixon opens, it usually stays open. sometimes it closes when comp cools ,but could open any moment .i would check all external power elements as well .
good luck

[1mikeefc1]

I'm with goshen on this one, once the comp is running sounds like the windings are open circuit then as the comp cools down you get closed circuit again would change compressor.