Greetings, all
I had a question - does a turbocharged propane engine driven generator needs to be derated for high altitude? I understand the need for derating for high altitude, since the air is less dense at higher elevations and it loses its effectiveness to cool down the engine. But for...
Hello All,
Does a TEFC type motor require electric heaters to keep it warm and dry when the motor is idle? Does it depend upon environment and if the area has high humidity. If there is high humidity, then higher chance of condensation?
Thanks for your thoughts.
Hello All,
What are uses and pros/cons of Alloy type O/L versus Solid state O/L for a single speed motor in the range of 20 HP? Does it depend on environment where a motor is installed? Cost?
Any thoughts on where you'd use either one would be appreciated. My understanding is that both types are...
Greetings All,
What is typical ratio between skW and rated kW of a gas generator? I know that gensets are capable of providing higher starting kVA for motor starting, but do they also provide higher skW for limited time? What is the limiting factor here.. is it the temperature rise on alternator...
Hello All,
Has anyone used a DC to DC converter in the past as battery charger to charge 12VDC battery on a genset? The project I'm working on doesn't have a reliable 120vac supply on site, but there is battery bank that can be used to maintain charge on the generator battery. Looking for 24VDC...
Hello,
For a CT installed indoors in a powerhouse, what is the "typical" or rule-of-thumb life cycle of a CT? What are factors affecting the life expectancy and is it common to see a CT fail in service? Typically, CT's are not maintained, so I was wondering what could be leading up to a...
Hi Gents,
I had a question - is the thermal factor rating on a current transformer refer to continuous or overload capability of an instrument to carry increase in current? For example, if 1000:5 CT has TF of 2.0 at 40 degree C ambient, does this mean that this device can carry 2000Amps...
Hello Gents,
I'm looking at a trend in PI for a water level value and the value is fluctuating below 0 feet and above 0 feet. To me that is strange, I'd expect the trend to be above 0 feet. What can I infer from this trend? When the sensor is reading & reporting a negative value, is that...
Hello Gents,
I notice that in Full Static Excitation schemes, a delta-delta connected PPT is utilized. Why delta-delta type? My thoughts are that to provide higher reliability - if one phase fails, you can still supply AC power to your power bridge converter via open delta connected PPT. Also, a...
Greetings,
Has anyone done offline Potential Transformer burden testing? Is offline PT burden testing more challenging to do than an online testing? Just wanted to hear from your experience.
Thanks,
EE
Hello,
Are there any concerns with locating HPU system and battery bank in the same pre-fab building from safety perspective? Any industry codes one would have to follow?
Thanks,
EE
Greetings All,
I have a question - I see a battery cell nameplate having a rating of 105AH 8 HR to 1.75VPC. Does this mean that the ampere hour capacity of the battery cell is 105AH? Why is "8 HR" included in the nameplate data..is this indicating that the battery can produce 13.125Amp...
Greetings,
Why do we typically see an open-delta PT having one of the secondary phases grounded? What is the purpose of grounding, to prevent phases from floating? We'd still get the same line-line voltage between VAB, VBC, and VCA.
Thanks,
EE
Hi Guys,
I was thinking about Fe and Cu losses of a power transformer. Do we expect the iron and copper losses to stay constant over the life of a transformer? I know that the total losses are a function of loading of the transformer, specifically the CU losses that are proportional to I2R...
Hey All,
Is there a reduction of maximum torque that should be applied to bolts due to the age of the bolts? If bolts have been in service for a long time, is there a possibility of damage to them if they were re-torqued to their maximum spec value?
Thanks,
EE
Hello,
I have been pondering about this topic lately, and figured I'd ask on the forum. Most of us here are professionals and often we go extra mile to meet the deadline or assure a quality product.
Please put your discipline, type of business and average hours worked a week.
Electrical...
Hi everyone,
What's the difference between UL listed/rated equipment and non-UL listed devices? Can a device that does not have UL label be as reliable and long lasting quality-wise? What would be a scenario where you would omit/forego UL label as your tech requirement?
Thank you,
EE
Hello,
Has anyone used a CT Analyzer to determine the accuracy class of a current transformer. If metering class and burden data rating were missing, and you knew the ratio of the CT, presumably you could inject current on the primary and measure the secondary to derive current ratio error in %...
Hello,
I apologize if this question was already asked on this forum, but is it a common(industry) practice to provide ground connection for Y-Y grounded PT's at the switchgear where the PT's are installed? If the secondary wiring(4-wire "Y") leaves the switchgear to control room, we should avoid...
