AP7723 automatic transfer switch - is it suitable?

[Anonymous user]

I'm thinking of purchasing a SURT6000XLI to protect an intel blade server: http://www.intel.com/content/www/us/en/modular-server/modular-server.html

I would like to have dual power redundancy but unfortunately the intel blade needs 3 out of 4 PSUs to run(they are 1000watt each). I was thinking of getting a AP7723 auto transfer switch, plug source A into the SURT6000XLI, Source B into mains.

The 4 PSUs of the blade server in turn would be plugged into the AP7723

Would the AP7723 be designed for such purpose? With 4 sockets left i also hope to plug in couple mmore servers,router and firewall as well. Would auto transfer switch be able to handle the load?

Thanks

Wil

[BillP]

We (APC/Schneider Electric) recommend placing a UPS between the generator and the ATS input. The UPS will condition the input voltage to the ATS to prevent thrashing. A second UPS should be used between the power utility and the other input of the ATS (which you already mentioned would be the SURT6000). This UPS will power the load while the generator starts and stabilizes. The UPS should be sized to allow time for the generator to be started and the time needed for the UPS attached to the generator to operate normally.

While the generator is starting, the generator voltage and frequency are not stable. If the ATS is connected directly to the generator, the ATS can switch to the generator input before the generator has stabilized. The load of the ATS will cause the generator voltage to dip.This dip can also shift the frequency of the voltage. Either of these issues can cause the ATS to switch to the other input.

even so, if you need to do this, then you will want to make sure you configure the ATS to have a low sensitivity and wide transfer range in order to best handle the generator directly.

When the ATS switches inputs, the ATS waits for a zero crossing of the voltage waveform. If the load has a power factor of less than 0.9, there can be significant current flowing. This will lead to arcing and welding of contacts.

Relay manufacturer specify contact life for resistive loads only and switching on the zero crossing. They won’t specify contact life at different power factors. Engineering cannot predict how long the contacts will last if switching loads with low power factors. Engineering does not recommend using the ATS with loads that have a power factor of 0.9 or less.

[Anonymous user]

Many thanks.

I will not be using the diesel generator for second source though (it will be just mains) The ATS will be using Source A (SURT6000) at all times unless theres maintenance planned or the UPS fails

Is this still ok?

Wil

[BillP · Accepted solution]

i think as long as it does not have any of the issues mentioned above that a generator has then it should be fine.