Loss of voltage

[tulum]

Hello,

Does anyone know of a very simple relay that monitors loss of 3 phse current and voltage. I need two from c contacts as the output.

I found some on the web but they all have 20 other functions with them. I just want to use the contacts in my control when the main controller opens.

Regards,
TULUM

 

[bklauba]

You could use a simple 3 ph solid state O/L device, such as one of the CEP7 series from Sprecher & Shuh. When a phase is lost, NC contacts open w/i 4 seconds.

What current and voltage levels are involved?

BK

 

[Skogsgurra]

Carlo Gavazzi makes a range of relays that monitor voltage and current in three-phase systems. They also have one that monitors power. Have a look at

http://productsonline.info/POL/itemDetails.jsp?uid=1109968207062&itemCode=DWB02CM4810A#

 

[tulum]

Thanks guys, I will take a look at the manufacturers websites.

The voltage is 3300V, 800A, however, I will use some PT's to bring the voltage down to 120.

Regards,
TULUM

 

[dpc]

tulum,

Where are you located?

 

[buzzp]

There are lots of low cost manufacturers, try SymCom Inc, Time Mark, SSAC, Entrelec, etc., heck Ill make you one.

I dont think thermal (non processor based) overloads have low current protection protection (underload). They do have loss of phase protection. But again this is not for low voltage situations, although LV will probably give you an overload condition.

 

[RRaghunath]

Tulum,

If you are not contemplating single phasing (considering it is 3300V system), you can use two auxiliary contactors with 120V AC coils connected phase to phase across PT secondaries. The contacts of these coils will signal the loss of voltage in the system and can be wired as appropriate to your scheme.

With regard to sensing loss of three phase current, use of bimetal overload relay elements on the secondary of respective feeder CTs can be a simple and economical solution. If you like to consider 'under current elements are available in most of the numerical current based feeder protective relays and possibility of using them can be explored.

Trust the above is helpful.