Testing Zs on an IPS system?

[Noob2013]

Hi all,

Does anyone know how to test the Earth Fault Loop Impedance on a monitored circuit such as IPS?

I have found in the past that even a Martindale Socket Voltage Tester can trip out the circuit as it is monitored.

I also found that no matter which way the neutral and line test probes were, the meter showed cross polarity. Is this due to the monitoring system?

Much appreciated.

 

[ImpededLoop]

It's not something I'm familiar with, but could you measure R1+R2 for the circuit and add it to Zdb?

 

[Farmelectrics]

whats ips

 

[Farmelectrics]

did you mean ups

 

[ImpededLoop]

Isolated power system

 

[ImpededLoop]

It's not something I'm familiar with, but could you measure R1+R2 for the circuit and add it to Zdb?

Actually, if it's a power system supplied by an isolating transformer, my earlier answer is wrong as there would be no reference to earth on the final circuit.

 

[Noob2013]

Yes IPS is Isolated Power System.

It's commonly used in operating theatres.

I have spoken to several electricians who have worked there and none of them know :S

 

[Flanders]

Would the zs be not applicable as its isolated
a so just do R1 R2 test .

 

[Lucien Nunes]

Zs is fairly meaningless on an IT system and I doubt you would want to test it in the usual way, as you will only see the monitoring input rather than any kind of supply impedance. R2 will confirm that the CPC is intact and any other tests would surely be as specified by the IPS manufacturer.

The tester will not be able to identify the polarity of an IT system, and since neither circuit conductor will be sufficiently close to earth for it to decide it's the neutral, it will show incorrect polarity either way. Most MFTs are intended to live their lives in TN-land!

 

[Noob2013]

Would the zs be not applicable as its isolated
a so just do r1 r2 test .

Yeah probably the best option.

On the flukes you can select Zs but only take a reading between L and N. So could also record that result and make a note of the situation.

 

[Engineer54]

Actually, if it's a power system supplied by an isolating transformer, my earlier answer is wrong as there would be no reference to earth on the final circuit.

In a healthy condition your right, but not on the occurrence of a first fault, but then the monitoring device will be letting everyone know that a (first) fault has occurred. Monitored IT supplies can commonly be called ''double fault'' supply.

Monitored IT supplied systems such as you would find in hospital operating theatres are designed along with other associated provisions, to provide a secure means of power without putting patients at risk...


Another area where IT supplies would regularly be seen, is in the mining industry....