SMT 3000 settings/options

[JoeK_KDS]

Our business (engineering) uses 4x SMT3000RM2UNC to protect the servers and network equipment. We also have a generator and transfer switch that automatically start and switch over after a set duration in the event of an outage.

1. Regarding the SMT3000, does one of the settings adjust a 'wait period' when returning from battery to line power? If able, I am looking to stagger the switching times so that all 4x do not switch to generator power at the same time. I believe this may be the 'Turn On Delay' setting, but the documentation is not abundantly clear.

2. We have also had issues with the SMT3000s not returning to 'Online' when supplied by power from the generator. This did work when 1st commissioned. But as of a recent test all 4x UPSs would only momentarily go online before returning to battery. Electricians and ourselves have verified that the power looks quite clean (120v, 60hz, etc), we've adjusted the sensitivity to 'low' but are still not successful. Is the UPS capable of indicating why it refuses to go online?

Note: I did try to find other posts similar to my issue, but was unsuccessful. Also, I am facility maintenance and do not have open access to the UPSs. All tests and requests need to go through and be supported by our IT department.

Thanks in advance,

Joe

[Teken]

The turn on delay is for the connected load(s) this option has no affect on the UPS transferring from AC line vs battery. You can adjust the upper and lower (voltage) transfer range of the unit.

Doing so will force the unit to accept higher / lower voltage before engaging its AVR circuit. Keeping in mind this doesn’t directly address the UPS transferring from AC to battery.

The (low) quality setting is the only thing that tells the UPS when to transfer over. I’d suggest you review the internal logs from the UPS to see what it thinks it sees in terms of voltage / frequency. Compare that to the actual UPS outlet when the lights out (generator) test is underway.

It’s not enough to just measure voltage & frequency. You must measure THD and view the sine wave on a scope. This will provide you the information as to how clean vs dirty the generator power is. A generator like any other motor requires ongoing maintenance and monitoring and as they age often times begin to output dirty power. More often than not it’s a timing issue, RPM, stator, generator, brush, to fuel related issues: Pressure, volume, filter etc.

At the end of the day it really doesn’t matter because the UPS is doing what it’s designed to do - and that’s provide clean uninterrupted power to the connected loads. 👍

Interested to see what the power looks like with a power quality meter attached when on generator at the UPS outlet. 

[JoeK_KDS]

Hey Teken,

Thanks for the response.

In our ongoing efforts we had discovered that the generator (outside of audible range) was struggling to maintain its speed set-point while cold. A technician has adjusted the fuel pressure and cleaned the throttle body which greatly help with this. The UPSs now accept the power ~98% of the time when set to 'low' sensitivity.

Thanks for the info about THD. I believe we have a decent oscilloscope onsite, just waiting on someone to assist with using it. I will see about a power quality meter.

I will also inquire about the logs.

Thanks,

Joe

[Teken]

Hi Joe,

Great to hear and please do mark this question answered or solution provided if so.

Rock On . . . 👍