Hello
Can a Current Transformer with a ratio of 50/5 be effectively utilized on a 1200A bus or incoming cables?
What are the key considerations when using this CT on a higher ampacity application?
Also, any recommendations for CTs that can accurately detect 48 Amps?
What is the nature of the loads? - Non-linear loads. Only loads on the system are switching power supply units L-N (277V)
Is distortion power factor a factor? Yes
Hello
I have a harmonic current spectrum from a system test performed which could be only loaded 25% of its rated load (the remaining loads are still under construction). All the loads are L-N well distributed. There is no other type of load in this system.
To obtain the full load (100%)...
Hello All,
Is anyone aware of a manufacturer or firm that makes (pre-fabricated) an enclosure with DC (up to 1000vdc) and AC contactor with 24vdc coil? Will be using this for testing PV inverters. The reason I ask is as pre-fabricated enclosure will be tested and listed as well. Attached is a...
Hello All,
Can someone help me with a link to interconnection requirements for California (SCE) when adding Energy Storage and PV to the existing office building? For both Export and Non-Export.
In the attachment, it says "Control power to the Shunt Trip with Lockout must be removed for a minimum of 0.25 seconds before the breaker can be closed". Why wait for 0.25 seconds what is logic behind...
Thank you, @jraef. Now I understand. In the manual on page 38, I see the kW also listed (attached snapshot). Here the total kW will be 66.7kW for the whole system correct?
I am working on short circuit calculations for a system. There is an HVAC unit (nameplate attached). I did verify (Unit Power Supply) the cable and upstream protective device do meet the minimum circuit ampacity and max circuit breaker size, respectively. I have the following questions about the...
Is there a REVERSE transfer switch? I have seen a transfer switch that switches a load between two sources. Is there an application or product which operates opposite to a typical transfer - switch between loads instead of sources (A single source with the option to feed a small ampere load vs a...
Hi @IonelHutz,
Understood :). Can you advise me on manufacturers who would have a heavy-duty contactor rated for 480V but have circuit coil voltage of 24 to 120V ac/dc? I did find Square D, and Eaton has few options.
Hello All,
I am looking for any ideas and a sample electrical design if available. A design to feed I want to connect and feed a separate load contactor-based design to switch between different loads when from a source. As shown in the attached picture (it is high level) the generator feeds the...
Hello All,
I am working on my first electrical design project which entails to size breaker, wire, conduit, grounding, etc. In the project, I need to design an electrical layout to have a switchboard which will have DERs (solar, Battery, and windmill) along with utility *& conventional...
I had a question about the CT wiring to the relay shown in the picture. I was wondering is there a reason to show the wiring swapped other than connecting the polarity to the polarity input of the relay.
Hello all,
I am working on prepping relay files for SEPAM. I see there is a setting mode of 10I/Is vs TMS (Time Multiplier Settings). In the SKM software, the selection is available to use either mode for curve selection. I was wondering based on experience why use one mode over the other when...
Hello All,
I was wondering if anyone has a spreadsheet template of an SEL relay (SEL-751 specifically( one has created with setpoints, I/O mapping and MODBUS mapping which I can use as reference to create one. The reason I ask is to get thoughts on how to present the MODBUS and I/O mapping in a...
In a motor protection application using relays, I have seen the trip circuit having a normally closed contact in the run circuit. What is the reasons to have normally closed contact in this application where is in normal feeder protection the relay contact is programmed as normally open? Is the...
