Maintenance for Static Switches

What do you mean by static swiches? How do these relate to the UPS units? SS?

No idea. Try to explain in more detail. Think it out more carefully.

Thank you. Too often we "industry speak" and people like me, who could occasionally make a contribution can't figure out what the question is.

Can you re-state your enquiry so that a politician could make you pay a tax on it?

Sincerely,

Oh Oh I am sorry, I needed to be more clear. Two redundanct UPS outputs will be connected to static switch input. The static swithc provides reduncanct supply to rack which houses the servers. In order to maintain the reliability of power this config is used in Data center. If one of power fails the static switches transfers the load to other source ( break time 4ms - same phase, up to 16ms-difference phase- inputs)

Static switch is the single point of failure in this scheme.

Let me know if any schematics are required.

Regards,

Hareesha

Reply to: hara143 #3

" Two redundanct UPS outputs will be connected to static switch input. The static swithc provides reduncanct supply to rack which houses the servers. In order to maintain the reliability of power this config is used in Data center. If one of power fails the static switches transfers the load to other source ( break time 4ms - same phase, up to 16ms-difference phase- inputs)

Static switch is the single point of failure in this scheme.

Let me know if any schematics are required. Regards, Hareesha "

Is SS in your Workplace or in UPS's System Module?

Make of UPS?

Actually UPS's having Redundant "Pwer Modules" are > 450KVA & have at least 3x 250KVA Power Modules, 1 System Modules having SS & 3Ph Power contactors to bypass after the SS has taken-over to take all the power thru them, Alarms & indications Power-Sharing, Voltage-level controls.

SSs are simply 2-way Thyristors connected back-back in parallel to make AC go to load.

3 such pairs are for 3 phases. Once the power is shifted a contactor takes over & SS goes to standby or remains there but do not pass any current while Contactor passes the whole current.

As soon as the power module on-load fails, contactor drops, Firing-pulses to SS thyristors stopped, & the power module goes off-load & isolated from power [I/P & O/P sides]

In UPS all the power modules are connected in sync of phase- & Voltage and sharing power.

When a power module fails it is isolated by System Module.

After the repair is done it is powered on & connected to share but will take time to sync with system.

it may differ from system to system. Ant-how it was a general procedure.

You can send me a message having your email address, I will try to resolve if you can send me Cct Diag etc

Depends on the Static Switch. Most 3 phase models have an internal maintenance bypass electrical pathway. For this type of STS you should be able to manipulate breaker or switch line-ups in order to make the STS safe to maintain.

It sounds like what you are trying to do is bypass the STS by making your own external maintenance bypass circuit. If you are trying to do this without an interruption of power to the PDU, this is a dangerous idea. You may manage to parallel the output of the STS with another source. However, you will probably cause a voltage transient that will damage your mission critical equipment.

A better idea is to go ahead and shut down during the STS maintenance. If you have dual corded equipment, go ahead and remove the STS. Have one of the STS power sources provide power to one of the PDUs. Have the other source power a second PDU. Plug one cord into each PDU. Viola! No more single point of failure.

Thanks Eric,

We use STS for each of the rack rather than at main PDU. This is kind of containment. All dual core server 1U servers are single source machines and has more tolenrance than some older machines. I know by plugging i can create switching transients. I really do not know, When i did this experiment with Normal power ( utility power) i could not see much of the transients. May be I am wrong.

But do you really think that, by plugging same phase of same UPS can create issues.

Hara143