ECN Forum Forums Technical Discussion Electrical Theory and Applications Discussions on: HID CWA Ballasts

Hello again, James!
Definitely not bothering me at all!

Per the last post, I'll quote the appropriate text above my replies.


Likely, this would be a "Standard" Linear Reactor type setup.
From the Connection description at the end of the latest post, it really points towards a Linear Reactor setup.

Here is a Schematic for the Linear Reactor Ballast, which is used with either a Metal Halide Pulse Start Lamp, or an HPS Lamp:



Here is the CWA Ballast Schematic for Pulse Start Metal Halide and HPS Lamps:



More information may be found regarding the Linear Reactor Ballasts at the Technical Reference area. Just click the link text to go there (the underlined "Linear Reactor Ballasts" text).

In all connection examples the "Common" Conductor, used with HID Ballasts, does not necessarilly need to be the System's Grounded Conductor in order for the Assembly to operate correctly.
In many scenarios - such as connections using input Voltages like 208 VAC and 240 VAC, these would definitely not use a Grounded System Conductor on the "Common" side of the Ballast, but instead would use an "Opposing Phase" Ungrounded Conductor on the "Common" side of the Ballast.

As far as the Capacitor in this case - and the setup being a simple Linear Reactor Ballast, the input would have an "Optional Capacitor" connected, to improve the Power Factor seen by the Power Supply.
A bit more detail in the next reply below.


Typically a Capacitor will be used to improve Power Factor, as seen by the Power Supply, but in some cases of HID Ballasts, it plays a secondary role; Lamp Regulation (along with PF correction).

Lamp Regulation is a bit lengthy of discussion (so is Power Factor!), so for this case we will just cover the simple parts of the P.F. thing.

The Ballast and Lamp combination, under normal operation, results in a Lagging Power Factor (an Inductive Reactance load). The Power Factor is around 50% (0.5) - which would result in an input Current flow of twice the level required to deliver the True Power rating of the Lamp.

Example:
100 Watt Lamp,
System Voltage = 100 VAC
Power Factor = 0.50
Input Amperes = 2.0 Amps @ 100 VAC,
Input Apparent Power (Volts × Amps) = 200 VA (Volt-Amps).
The VA figure carries the True Power (Wattage), along with the Reactive Power (VARs, or Volt-Amps Reactive).

In order to keep from having to "Recharge" the Ballast with the Reactive Power (the "VARs"), we can "Store" them near the Ballast Load, using a Capacitor.
Now, the Ballast only needs to be "Charged" minimally with the VARs, and they are "Kept" near the Ballast Load via the Capacitor.
The input VA is reduced, and so is the input Line Amperes, and consequentially, the overall Power Factor has been improve by including the Capacitor.


This appears to be a Linear Reactor setup.
Check out the Schematic, and compare it to your Ballasts, then let me know if they are Linear Reactors.


As mentioned previously, the Ballast does not require a "Neutral Type Conductor" (Grounded Conductor), only that the input be a "Usable 2-Wire Circuit".
By this I mean a Circuit - this being of at least two individual Conductors, with a Potential Difference between them - and being ones that are intended for use as "Normal Circuit Conductors".

"Normal Circuit Conductors" being Ungrounded And/or Grounded Conductors, not Equipment Grounding Conductors (or Grounded/Bonded Equipment) being used for Normal Circuitry.

"Potential Difference Between Conductors" meaning "A Substantial Voltage Reading Between Conductors", which results in a Current Flow.
All above to be designed and installed intentionally and safely, per common techniques.

So, to make some sense here , either two Ungrounded Conductors - of opposite polarity, or one Ungrounded conductor and one Grounded Conductor, may be used to drive the Ballast.
In the case a Grounded Conductor is used, it Should be connected to the "Common" section of the Ballast.


Most ballasts will use Capacitors for both P.F. Correction and Lamp Regulation.
Linear Reactor types use the Capacitor solely for P.F. Correction.

You are correct about the Ballast being like an In-Line Resistor to limit the Current!
That is the primary function of all Ballasts - for HID Lamps, Fluorescent Lamps and Neon Lamps.
These Discharge Lamps have a Negative Resistance effect, which allows them to draw high levels of Current, in a "Domino Effect" fashion.
The higher the Current flow is, the more conductive the Lamps Arc becomes - and therefore allows more Current to flow - which makes the Arc more conductive... etc., to the point where the Lamp "Kills Itself"

Let me know if this reply describes what you need, or if there are additional questions.

Scott35