Probe start and pulse start 400 watt metal halide ballast types
There are only two types of starting methods for HID ballasts:

Probe start 400 watt metal halide ballast:
Probe start ballasts are the older type and not very easy on the HID lamp. Electrons jump across the arc tube between two operating electrodes. Once the lamp is started the starting probe electrode is removed from the circuit.

The problem with this starting method is that it takes a long time for the lamps to warm up and reach their full brightness. Also, the re-strike period is much longer.

Pulse start 400 watt metal halide ballast
Pulse start ballasts don’t use a starting probe electrode. Instead, they uses a high voltage igniter that works right alongside the ballast. This technology pulses to start the lamp.

This way, the life of the lamp is actually extended, and the lumens don’t depreciate as fast. Pulse start ballasts are also known for being more energy efficient than probe start ballasts.

Types of 400 watt metal halide ballast for lighting tower

lighting tower ballasts belong in their own category. There are all types of them and their purpose is to power a lamp at reduced light output for up to 290 minutes. Also, did you know that most emergency ballasts recharge themselves after each use? That is, until they reach full life capacity.

Constant Wattage
Autotransformer lighting tower ballast
These ballasts also are called regulated or
autoregulator ballasts.

The constant wattage
autotransformer (CWA) ballast consists of two coils on
a core of steel and a capacitor in series with the lamp.
CWA ballasts perform the basic jobs of current limiting
and voltage transformation.

In addition, CWA ballasts
are always high power factor ballasts. They have
starting currents that are less than the operating current.
In regard to voltage regulation, CWA ballasts offer
significant improvements over reactor and lag auto
designs. CWA ballasts are designed to handle a +10%
line voltage variation.

Over this range, they will maintain
lamp wattage within +5%, a four-fold improvement over
reactor and lag auto ballasts. They also can handle
sudden dips in line voltage without lamp shutdown. This
type of ballast is most commonly used in area, sports
and indoor HID lighting.

Constant Wattage Ballasts

Also called isolated regulated-premium constant
wattage ballasts, this ballast design limits current,
performs voltage transformation and provides the best
lamp wattage regulation available. They are designed
to operate over a voltage range of +13%, maintaining
lamp wattage to within +2.5%. Constant wattage (CW)
ballasts have a high power factor and a lower starting
current than operating current. These ballasts are
similar in construction to CWA ballasts.

HPS Mag Reg

Also called reg lag, mag reg ballasts are used to meet
HPS lamp wattage requirements on systems having a
+10% voltage variation. These are high power factor
ballasts that have lower starting than operating current
requirements. The mag reg transformer consists of
three isolated coils on a core of steel.