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6440 - Transformer Protection Triggered

SMA Manual Recommendation 

Error No.Explanation Corrective measures
6440Hermetic protection of the transformer no longer exists • Check external transformer. 

Swapping Transformer Wiring to Prototype Transformer:

NOTE: If alarms cables cannot be rewired, the alarms can be bypassed at the X9703 so that the inverters can run temporarily. This will bypass all transformer alarms. Jumper pin 1 to 3, 5 to 7, 2 to 4, and 6 to 8.

NOTE: Ensure the new transformer has adequate nitrogen so that the pressure alarm is not active.

NOTE: Be sure to check the top of the pressure gauge is wired properly. 51 and 52 should be on the normally closed terminals. This can be tested with adequate pressure and by checking the 24Vdc is present on both positions. This can only be tested once you've connected the conductors on the terminal block and the relays.

    1. Recover a set (2) of transformer-alarm cables from a spare (failed) transformer in the graveyard.

    2. Open the gauge cabinet and take photos to document the positions of all of the conductors before removing anything.


    3. Disconnect all of the wiring for each of the transformer alarm cables. There is no need to disconnect any jumpers, these should already be installed in the new transformer. Only the conductors coming from the transformer alarm cable.

    4. Once all of the conductors are loose and the cable is ready to be removed, unscrew each ring fastener on the inside of the gauge cabinet which holds the cable to the frame. You might consider using a flat tip screwdriver and a mallet if you don't have the proper tools.

    5. Remove the cable guides using a phillps screwdriver so that each of the cables can be pulled away from the cabinet.

    6. The cables can now be removed. Store all of the parts safely to transfer to the new transformer.

    7. At the new transformer, begin by drilling two new holes and threading the cables through. Tighten each ring fastener to hold the cables in place.

    8. Begin reconnecting each of the conductors into the terminal block. These should closely match the unit they were removed from. If you have trouble, reference transformer 15.A.3 which also used a prototype transformer.


        a. It is easiest to connect one cable following a general convention first. Install one cable with both conductors at the back of the top switch. Then install the remaining relay conductors in the same location on each relay down the row. Repeat for the next cable. This will ensure no conductors cross and get jumpered together on the relay block.


    9. Once everything is connected, power on the inverters to test the circuits. The relays should display a green light. 

        a. If all of the relays are without lights, locate the supply and begin troubleshooting if a connection is jumpered creating a short. It's often helpful to disconnect all of the connections and test one at a time.

        b. If one relay is not lit, troubleshoot that individual circuit.

        c. Important to make sure that the pressure switch is wired for normally closed operation. This was miswired in the prototype installed in 15.A.3. Test this circuit and this might restore the missing relay.


    10. Be sure to test the selector switch in both positions.

Prototype schematic reference:

Old schematic reference:

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