GE G8.5 brochure Superimposed ignitors, Impulser ignitors, Other ignitor related considerations

Superimposed ignitors

In many installations Ceramic Metal Halide lamps are operated from a conventional magnetic ballast in conjunction with a superimposed ignitor. These ignitors generate starting pulses independently from the ballast and should be placed close to the lamp, preferably within the luminaire. Wiring between ignitor and lamp should have a maximum capacitance to earth of 100pF (length equivalent to less than 1 Metre) - contact ignitor manufacturer for details of specific ignitor types. A typical circuit diagram is shown:

Typical superimposed ignitor circuit

Phase
Ballast
PFC Capacitor		B
	Ignitor	Lp
		N
Neutral

Impulser ignitors

Impulser type ignitors use the ballast winding as a pulse transformer and can only be used with a matched ballast. Always check with the ballast and ignitor supplier that components are compatible. Longer cable lengths between ballast & ignitor and the lamp are possible due to the lower pulse frequency generated, giving greater flexibility for remote control gear applications. Ignitor pulse characteristics at the lamp must however comply with specified minimum values for ConstantColor CMH™ lamps under all conditions.

Typical impulser ignitor circuit

Phase
Ballast
PFC Capacitor	Ignitor
Neutral

Suitable Ignitors

Suitable high-energy (superimposed) ignitors recommended by control gear manufacturers are listed below. Check 0with suppliers for their current range of ignitors. Lamp re-starting under warm lamp conditions can take up to 15 minutes. Suitable ignitors to achieve a warm restart of less than 15 minutes include the following, however the list may not be fully inclusive:

Maker			Products
APF	SP23
BAG Turgi	NI 150 SE	NI 150 SE-TM20	MZN 150 SE-C	NI 400 LE/3.5 A	NI 400 LE/3.5 A-TM20
ERC	AZ A 1.8	AZ P 1.8	AZ P 1.8 T3	AZ P 1.8 T3	AZ P 3.0 T3
Helvar	L-150	LSI-150T20
Magnetek/May & Christe	ZG 0.5	ZG 2.0	ZG 2.0D	ZG 4.5D
Parry/Parmer	PAV400	PCX400	PXE100
Philips	SU20S
Thorn	G53459	G53498	G53476	G53504.TB
Tridonic	ZRM 1.8-ES/B	ZRM 2.5-ES/B	ZRM 4.5-ES/B	ZRM 6-ES/B	ZRM 2.5-ES/B
Vossloh-Schwabe	Z 150	Z 150 K	Z 150 K A10	Z 150 K A10	Z 250

Other ignitor related considerations

Timed or Cut-out Ignitors

The use of a ‘timed’ or ‘cut-out’ ignitor is not a specific requirement for ConstantColor CMH™ lamps but it is a good optional safety feature worth considering to prolong ignitor component life. The timed on-period must be adequate to allow lamps to cool and restart as described below. A period of 10-15 minutes continuous or intermittent operation is recommended before the ignitor automatically switches off. Timed ignitors specifically offered for High-Pressure Sodium lamps where the period of operation is less than 5 minutes are not suitable for ConstantColor CMH™ lamps.

Hot Re-strike

All ratings re-strike within 15 minutes following a short interruption in the supply. Actual re-strike time is determined by the ignitor type, pulse voltage and cooling rate of the lamp. Instant hot re-strike is only possible using a suitable very high voltage ignitor and a double ended lamp. GE Lighting should be consulted when considering use of an instant hot re-striking system.

Warm Re-starting

The combined characteristics of ceramic arc-tube material and vacuum outer jacket result in ConstantColor CMH™ lamps cooling relatively slowly. It is possible with low energy ignitors to reach the required breakdown voltage but not create a full thermionic discharge. Under these conditions the lamp can remain very warm and be prevented from cooling to a temperature at which the arc can be re-established. To avoid this, turn off the power supply for approximately fifteen minutes or change to a suitable high energy ignitor from the list given in the superimposed ignitor section.

Fusing Recommendations

For a very short period immediately after switch-on, all discharge lamps can act as a partial rectifier and a conventional magnetic ballast may allow higher than the normal current to flow. At switch-on the short duration surge current drawn by the power factor correction capacitor can be high. In order to prevent nuisance fuse

failure at initial switch-on, the fuse rating must take these transient conditions into account. A separate technical data sheet providing additional explanation and information for the fusing of High Intensity Discharge lighting circuits is available from GE Lighting.

Fusing of individual fixtures is recommended, in order to provide added protection for end-of-life conditions when lamp rectification can also occur.

Number of Lamps	1	2	3	4	5	6
35W Fuse Rating (A)	4	4	4	4	4	4
70W Fuse Rating (A)	4	4	4	4	4	4
150W Fuse Rating (A)	4	4	4	6	6	10

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