Re: [APD] Ballast electronic or magnetic?

["S. Hieber" <shieber at yahoo_com>]

Power factor should be better with electronic ballasts but unlikely to be unity since they employ inductors.

Most electronic ballasts that I have seen have relied on the basic principle that less induction is required to impede current at higher frequencies. The highger the frequency, the fewer Henries required to present a given level of impedance.

These electronic ballasts have inverters that increase the electric mains' frequency from 60 Hz (in the USA) to several thousand or even tens of thousands of Hz. The ballast coil can then be much smaller, yielding far fewer Henries, while still adequately impeding the current through the bulb (i.e., acting as an electrical ballast to prevent excess current from passing through the bulb). Other features are sometimes added to the basic circuit (progammed or soft start) voltage followers and controllers, etc., but the basic design is stepped up frequency and smaller coil. The smaller inductor will have less impact on the shift between current and voltage, but the power factor is unlikely to be unity.

Surely, there are ways to create ballasts without the use of coils, employing more complicated starter circuits, but such designs are not nearly so elegant or cost effective as the basic inverter and coil design.

sh


----- Original Message ----
From: Raj <rajendrakumargg at gmail_com>
To: aquatic plants digest <aquatic-plants at actwin_com>
Sent: Tuesday, November 28, 2006 2:17:23 AM
Subject: Re: [APD] Ballast electronic or magnetic?


Bill,

        Go for electronic, its more power efficient. It will pay for itself.
Power factor is unity (non inductive), your timer contacts will last longer.

Raj

> 
>1. Should I get electronic or magnetic ballast? The magnetic is  cheaper.
> 

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