Power Requirement for AP 1500

Unanswered Question
Apr 17th, 2007
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Hi Sir,


I found the following from Mesh 1500 datasheet for its power requirement,


95?260 VAC, 47?63 Hz

Power over Ethernet: 48 VDC, +/?10 percent


However, my contractor requested me to give him in Watt as UPS is provided to it. Can anyone show me the formula to do so?


Thank you.

Delon

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retiredmarine Tue, 04/17/2007 - 04:01
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The basic rule of physics that "watts = volts x amps" is based on direct current (DC) circuits. AC is more efficient but when it hits the transformers, it suffers from reactance.

Reactance reduces the useful power (watts) available from the apparent power (volt-amperes). Power Factor (PF) is the ratio of these two numbers. Therefore, the actual power formula for AC circuits is "watts = volts x amps x power factor." Unfortunately, the PF is rarely stated but generally is a number of 1.0 or less, and about the only thing with a 1.0 PF is a light bulb.



Figure out total loading of product Amps (A) Watts (W).

Multiply voltage by amps (V x A).

VA x 135%= the size of the UPS you would need.

* Estimated Average Growing Space 135%


(Amps)


A. Ex: 1 PC= 2A 1 Monitor=1.5A, Total= 3.5A


3.5A x 120V= 420VA x 130%= 546VA.


B. Ex: 1 DVR = 300 Watts, 5 CCTV = 350 Watts, Total = 650 Watts


W = P.F. x VA, Direct UPS JP X series P.F = 0.7 & VP series = 0.6


650 W = 0.7 x VA , VA =650w/0.7, Total Loading = 929VA


Right size UPS: 929 VA x 135% = 1254VA.


The recommended size UPS for example a. is 600VA


The recommended size UPS for example b. is 1400VA

c.ong Tue, 04/17/2007 - 06:54
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Hi David,


Thank you for your explanations and examples.

Can I know from the data sheet of the Mesh AP 1500, what is the power requirement which the equipment requires?


From P = IV, V=48V as per data sheet but I do not know what is the I (ampere) required? How can I compute the P in Watt?


Thank you.

Delon

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