Quantcast TIME DELAY RATINGS

Share on Google+Share on FacebookShare on LinkedInShare on TwitterShare on DiggShare on Stumble Upon
Custom Search
 
  
 
2-26 TIME DELAY RATINGS Circuit breakers, like fuses, are rated by the amount of time delay. In circuit breakers the ratings are instantaneous, short time delay, and longtime delay. The delay times of circuit breakers can be used to provide for SELECTIVE TRIPPING. Selective tripping is used to cause the circuit breaker closest to the faulty circuit to trip. This will remove power from the faulty circuit without affecting other, nonfaulty circuits. Figure 2-22 should help you understand selective tripping. Figure 2-22.—Use of circuit breakers in a power distribution system. Figure 2-22 shows a power distribution system using circuit breakers for protection. Circuit breaker 1 (CB1) has the entire current for all seven loads through it. CB2 feeds loads 1, 2, 3, and 4 (through CB4, CB5, CB6, and CB7), and CB3 feeds loads 5, 6, and 7 (through CB8, CB9, and CB10). If all the circuit breakers were rated with the same time delay, an overload on load 5 could cause CB1, CB3, and CB8 to trip. This would remove power from all seven loads, even though load 5 was the only circuit with an overload. Selective tripping would have CB1 rated as long time delay, CB2 and CB3 rated as short time delay, and CB4 through CB10 rated as instantaneous. With this arrangement, if load 5 had an overload, only CB8 would trip. CB8 would remove the power from load 5 before CB1 or CB3 could react to the overload. In this way, only load 5 would be affected and the other circuits would continue to operate. PHYSICAL TYPES OF CIRCUIT BREAKERS All the circuit breakers presented so far in this chapter have been physically large, designed to control large amounts of power, and used a type of toggle operating mechanism. Not all circuit breakers are of this type. The circuit breaker in figure 2-23 is physically large and controls large amounts of power; but the operating mechanism is not a toggle. Except for the difference in the operating mechanism, this circuit breaker is identical to the circuit breakers already presented.


Electrical News
Tesla Model S – Australian Test Drive
Dave test drives one of the first right hand drive...
eevblog.com
What Apple Stuffed Inside iPhone 6 Plus
The iPhone 6 Plus packs a host of new tech...
eetimes.com
Secure WiFi Shield for Arduino Platforms
The Arduino Wi-Fi Shield 101 is designed to enable rapid...
eetimes.com
Digital Level Shifting
Do you need to take your signals to the next...
eetimes.com
Steve Wozniak Reacts to Latest iPhone
Being presented with his very own iCups communications system certainly...
eetimes.com
Five Challenges to FPGA-Based Prototyping
The state-of-the-art has progressed spectacularly since early forays into FPGA-based...
eetimes.com
Q'comm Does Watches, Glasses, Robots
Qualcomm showed design wins in smartwatches, VR glasses, and robots...
eetimes.com
Making The Internet of Things 'Easy Stupid'
IoT companies need to provide a positive user experience that...
blog.designersofthings.com
Cars Made to Order at Retail
Local Motors' sporty 3D-printed car, looking like licorice on wheels,...
eetimes.com
Friday Quiz: Units of Measurement
The ways we express units of measurement should be perfectly...
eetimes.com
Nvidia's Maxwell Lights Up Voxels
Nvidia's Maxwell, its new high-end graphics processor, opens up a...
eetimes.com
Backlash Coming on Car-to-Car Talk?
Vehicle-to-vehicle communications will be mandated in the US, but public...
eetimes.com
Training Opportunities Abound at ARM TechCon
ARM TechCon is only a few weeks away, and if...
eetimes.com
10 Top Video Parodies on User Interfaces
There have been some interesting videos of "user interface parodies"...
eetimes.com
Making Wearables Personal
Wearables should be as unique as the person who wears...
blog.designersofthings.com
Elastomeric Camouflage Switches Texture & Color
Inspired by nature's most skillful camouflage artists, MIT researchers harness...
eetimes.com
Infographic: A History of Wearable Tech
Take a stroll down wearable memory lane in this great...
blog.designersofthings.com
18 Views of the Silicon Horizon
Semiconductors are poised for high single-digit growth this year and...
eetimes.com
Power Week: Did We Just Avoid an 'Electric Armageddon?'
While a powerful solar storm this past week resulted only...
eetimes.com
 


Privacy Statement - Copyright Information. - Contact Us

comments powered by Disqus

Integrated Publishing, Inc.
9438 US Hwy 19N #311 Port Richey, FL 34668

Phone For Parts Inquiries: (727) 755-3260
Google +