Ballasts?

[Vintage18]

Whattup 420?
I'm about to start a little grow op in a 2.5ftX2.5ftX5ft. tent and I plan on using a 400W HPS. I have a ballast to go with it but I have no idea what ballasts are for. Can someone please explain to me how they work/why they're so important/are they really necessary?
I've done lots of research and seem to understand just about everything but this..

 

[PrairiePoet]

Ballasts stabilize the current through an electrical load. These are most often used when an electrical circuit or device presents a negative (differential) resistance to the supply. If such a device were connected to a constant-voltage power supply, it would draw an increasing amount of current until it is destroyed or causes the power supply to fail. To prevent this, a ballast provides a positive resistance or reactance that limits the final current to an appropriate level. In this way, the ballast provides for the proper operation of the negative-resistance device by appearing to be a legitimate, stable resistance in the circuit.

An example of a negative-resistance device is a gas-discharge lamp (HID, MH, HPS), where after lamp ignition, increasing arc current reduces the voltage drop.

Ballasts can also be used simply to deliberately reduce the current in an ordinary, positive-resistance circuit.

Prior to the advent of solid-state ignition, automobile ignition systems commonly included a ballast resistor to regulate the voltage applied to the ignition system.
Although LEDs are positive resistance devices, they have insufficient resistance to regulate their current consumption when operated from a voltage controlled source, so ballasts are used to control the current through the LED. Because the power dissipation is minuscule, simple resistor ballasts are normally used.

 

[ilikebike]

a ballast is just one part of the light system that you need.

Light kit consist of

-HPS Bulb (the actual lamp you screw in)

-Reflector (these typicly have a M59 Socket built in, that is what you screw the bulb into)

-Ballast (this is what is going to be plugged into a wall outlet, this will have 2 cords running from it)

-Cord ( Connects from the reflector socket to the ballast )

-Power Cord ( From the ballast to wall outlet )

There are all kinds of different ballast, you probably want to get yourself a 400w Dimmable ballast you can find them for a good price on eBay, you can also find cheap reflectors on there as well.

I know you already bought the 400w bulb but im pretty sure our sponsor DigitalGrow at JD Lighting would be happy to put a 600w light kit together for you at a reasonable price

JD Lightings Hydroponics

 

[Vintage18]

Wow I never knew ballasts had so much purpose. Thanks for the explanation guys I kinda understand how they work now

 

[GigaGrew]

PrairiePoet
Great post, thank you.

 

[Wolfweed]

Hi can anyone recommend a digital ballast for hps lamp that can adjust output by 50% / 25% etc?