Hi. I recently had a Growatt SPF 5000 with a Hubble 5.5KW battery installed. A couple of days later, my garage door motor stopped working. Automation guys came out and diagnosed a burnt out coil (garage door motor is around 29V if my memory serves me correctly  - ET Blu). They changed the coil and a couple of days later, the same happens. Before installing another, they took away the motor and tested it off-site. Ran for a few days without issue. Brought it back to my place, installed it and also installed an Ellies surge protector to be safe. A few days later, the coil burnt out again. 

I had the electrician remove the garage circuit from the inverter supply and the problem disappeared. 

A few weeks later, I installed a new sliding gate motor and the electrical forgot that it was to be connected directly to Eskom supply and not to the solar back-up supply. A couple of days later, the brand new sliding gate motor stops working. Another burnt-out coil!

Something in the solar supply is clearly causing the coils to blow. My initial thought was the frequency setting on the inverter, which I've checked - and is at 50Hz. The installer has indicated that he will take the unit in for an inspection as its still under warranty. 

Does anyone have an idea what could be causing this? All suggestions would be most appreciated.

Thanks in advance! 

2 hours ago, Bashir said:

I recently had a Growatt SPF 5000 with a Hubble 5.5KW battery installed. A couple of days later, my garage door motor stopped working. Automation guys came out and diagnosed a burnt out coil (garage door motor is around 29V if my memory serves me correctly  - ET Blu). They changed the coil and a couple of days later, the same happens. Before installing another, they took away the motor and tested it off-site. Ran for a few days without issue.

Hi Bashir,

that is really very, very strange! These are 24V DC motors powered either from battery or a rectifier. If the inverter waveform is other than sinusoidal, I would rather expect the rectifier transformers to burn. In addition the operating time of the motors is something less than 20 seconds. I don't see how they can get burned in such a short time.

I have 2 garage door and one gate motor from ET Blue that operate now for some 18 months on my Axpert/Synerji inverters with absolutely no problem. The gate motor doesn't even run on the rectifier, but on the battery. There is only a trickle charger to recharge the battery.

Check out the voltage the motors are fed with in operation and in standby condition when powered from inverter, compared with grid power. Measure with the multymeter in both DC and in AC setting. I suspect AC going to the motors when in standby but cannot explain where it could come from. Could it be an earth bonding problem? Is the neutral of your inverter correctly earth bonded?

 

14 hours ago, Beat said:

Hi Bashir,

that is really very, very strange! These are 24V DC motors powered either from battery or a rectifier. If the inverter waveform is other than sinusoidal, I would rather expect the rectifier transformers to burn. In addition the operating time of the motors is something less than 20 seconds. I don't see how they can get burned in such a short time.

I have 2 garage door and one gate motor from ET Blue that operate now for some 18 months on my Axpert/Synerji inverters with absolutely no problem. The gate motor doesn't even run on the rectifier, but on the battery. There is only a trickle charger to recharge the battery.

Check out the voltage the motors are fed with in operation and in standby condition when powered from inverter, compared with grid power. Measure with the multymeter in both DC and in AC setting. I suspect AC going to the motors when in standby but cannot explain where it could come from. Could it be an earth bonding problem? Is the neutral of your inverter correctly earth bonded?

 

Very interesting.  Being a DC permanent magnet for the field motor there is no oil in the motor that can burn out. Only the whole armature. As said the motor runs of the battery after the power supply transformer where the output is fed to a voltage regulator to provide the 13.6/27.2V to charge the battery/ies.

I fail to see what coil is being replaced. Nothing to do with AC supply.

Thanks @Beat. Keen to try all suggestions and will provide an update after having the earth - neutral bond checked. 

@Scorp007The automation guy referred to the blown coil as a "toroidal transformer" - and it looks like the photo attached. Once it blows, there is a buzzing sound audible. 

 

Thanks Bashir. It makes sense. The ET unit is one of the few makes that can in fact run on the power supply and not like others that need the battery to drive the motor.

A test on the DC side of the rectifier will confirm what the output is from the transformer.

If you have the chance to check the blown transformer, I would suggest checking what side of the transformer is burnt (low voltage coil or high voltage coil). It may provide a clue to where the issue is.

10 hours ago, Bashir said:

Thanks @Beat. Keen to try all suggestions and will provide an update after having the earth - neutral bond checked. 

@Scorp007The automation guy referred to the blown coil as a "toroidal transformer" - and it looks like the photo attached. Once it blows, there is a buzzing sound audible. 

First, it is easy to check the neutral to earth bonding. Measure the voltage between neutral and earth on the inverter output terminals. It should not be more than a fraction of Volt, assuming (verify!) that the earth wire is connected to earth in the DB.

Second, the "coil" you show is the toroid core transformer for the rectifier of the ET garage door motor. If that has burned, it suggests that there is a wave form problem with the inverter, assuming that the output voltage is correct 230V ±5% (measure!). That should be resolved by the inverter supplier. It might be a repairable fault or a design flaw. Other appliances are at risk. Is there a possibility to have somebody take an oscilloscope picture of the waveform?

@Mauritius B thanks! The high voltage side was blown. 

If your battery voltage is low, some inverter types will cause the usually near-perfect sine wave output to become clipped. For an extreme example, see here. This can cause heating of certain types of load, I think mainly motors and transformers. 

The Growatts were at one point based on the Axpert design, so they might have the same problem. The mania with allowing ultra high battery voltages is the root cause. Only a few battery types needed 64 V to really fully charge, and those are flooded lead acid, which are becoming less and less common.

If I understand the issue correctly, the only problem is that the power supply for the motor is failing. Basically, the transformer is blown without any apparent reason but there are no issues with the motor or the electronics.

I guess the power supply is used to power the motor and the associated control electronics and it provides a voltage around 24volts.

My suggestion: can you get a switching power supply instead of a transformer one and test the system with it?

As switching power supplies are rectifying mains AC directly, any waveform issue could be avoided.

 

I have been running my Gate motor off a 50 Watt Solar panel and a cheap 10 Amp charge controller now for around 8 years. I have kept the 7.2 amp hour 12 Volt battery in the motor housing and have no other supply connected to the unit. In the 8 years I have replaced around 3 to 4 batteries and replaced the plastic rail mounted to the gate twice. Keep it simple and to one supply only. I have not converted my garage door openers to solar yet but will do this soon due to the doors not working at all without utility power. This is a major problem when the utility is down I am not able to get into my garage. The garage motors work off 2 x 6 volt batteries in parallel and appear to be a little light on out put current to open the doors on their own.

4 hours ago, Mauritius B said:

If I understand the issue correctly, the only problem is that the power supply for the motor is failing. Basically, the transformer is blown without any apparent reason but there are no issues with the motor or the electronics.

I guess the power supply is used to power the motor and the associated control electronics and it provides a voltage around 24volts.

My suggestion: can you get a switching power supply instead of a transformer one and test the system with it?

As switching power supplies are rectifying mains AC directly, any waveform issue could be avoided.

 

I would just put the garage door on 230V AC from the grid and compare voltages between the grid and the inverter.

It would be a good call to at least find out if the N to earth bonding has to be done as has been indicated to protect other equipment running on the inverter. Whatever is done do feel if the transformer gets hot as it will be hours before the HV winding starts to short circuit.

3 hours ago, Venom said:

This is a major problem when the utility is down I am not able to get into my garage. The garage motors work off 2 x 6 volt batteries in parallel and appear to be a little light on out put current to open the doors on their own.

The ET-Blue garage door and gate openers have enough 24V battery capacity (if healthy) for over a dozen cycles in case of power blackout. However there is a different design between the two types. The garage door motor has an enough powerful rectifier to operate from 230V without battery. Its battery is only backup for the case of power failure. The gate motor on the other hand has only a trickle charger and could not operate without battery.

Both types could be operated on solar panels with enough power to cover the need even on cloudy days.

7 hours ago, Mauritius B said:

My suggestion: can you get a switching power supply instead of a transformer one and test the system with it?

Would be rather difficult and only for an experienced handyman to accomplish as the the power supply is integral part of the motor package.