OSRAM POWERTRONIC PT-FIT I ECG for HID lamps, with cable clamp - Manual (Page 23)

THE PRODUCT IN OPERATION
2.3.8. ECG's ability to withstand frequent on/off switching
The ability of electronic control gears to withstand on/off
switching is always determined in the form of the number
of possible lamp starts per day. By multiplying this number
with the expected service life of the gear, the total number
of switchings for professional electronic control gear can
be calculated.
For HID-ECGs, however, there are a number of special
factors:
• High-pressure discharge lamps, due to the physics of
their lamp technology are not designed for frequent
switching, since, after being switched off a cooling time
of roughly between 3 and 15 minutes is necessary
be fore switching on again.
• In typical HID applications, therefore, there is only a
small number of switches per day.
• Due to the ignition time limit in the ECG, after a particular
number and duration of unsuccessful attempts at starting
up the lamp, the ECG is shut down.
Switching rhythm tests have shown that POWERTRONIC ®
ECGs can execute 40,000 lamp starts, which corresponds
to one lamp start per hour over a service life of 40,000 hours.
2.3.9. Short-circuit strength
With POWERTRONIC
® ECGs, the secondary outputs are
short-circuit-proof for approx. 5 minutes. However, any
short circuit between a lamp connection and the casing/
protective earth should be prevented at all costs, since
such an accidental fault to ground will lead to the certain
destruction of the ECG.
2.3.10. Switch-off criteria and mechanisms
One of the decisive advantages of lamp operation using
an ECG over a CCG is the active and intelligent protection
mechanisms provided by the ECG in order to ensure safe
and reliable lamp operation. Below we list the most impor-
tant causes of failure of high-pressure discharge lamps
along with the corresponding shutdown mechanisms
provided by the ECG.
2.3.10.1. Monitoring lamp voltage
One decisive parameter for ensuring safe and reliable
operation of your lamp is its lamp operating voltage.
POWERTRONIC
® ECGs therefore carry out permanent
monitoring of the lamp's operating voltage. If the lamp
voltage exceeds or falls below the limits defi ned for it,
then the device switches off, as proper operation of the
lamp can no longer be guaranteed and there is a strong
probability that the lamp may be running outside its
re quired specifi cations.
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2.3.10.2. Ignition time limitation
The EN 61347-2-12 safety standard requires that ECGs for
high-pressure discharge lamps with ignition voltages of
above 5 kV provide a defi ned shutdown of ignition voltage
after a particular length of time. POWERTRONIC
® ECGs –
despite having ignition voltages of less than 5 kV – are fi tted
as standard with an ignition time limit. That means that the
ECG will shut down after a defi ned time period without
successful ignition of the lamp. In order to allow a re-
ignition of the lamp with ECG after a cooling period, the
shutdown of the ECG happens after 20 minutes. It will
once more become possible to ignite the lamp after a
short mains interruption (t > 0.5 seconds). According to
the above-mentioned standard, an independent autostart
function by the ECG after a defi ned time period
(e.g. 3 hours) is not permitted.
2.3.11. Lamp shutdown at end of life
The end of the service life of a high-pressure discharge
lamp may occur for a number of reasons.
Possible reasons for this might be:
• Leaky arc tube or outer bulb
• Increase of the re-ignition peak
• Breakage of the leads or electrodes in the arc tube
• Oxidation of the base contacts due to arcing in the socket
• Explosion of the lamp (HCI and HQI lamps only)
POWERTRONIC ® ECGs generally operate metal halide
lamps and high-pressure sodium vapor lamps safely and
reliably. Of particular interest in this regard is their ability to
recognize and control End of Life effects (EoL effects) of
the lamps.
The intelligent ECGs are capable of detecting a variety of
EoL modes in the lamps and to shut them down accordingly.
The following operating situations and discharges in the
outer bulb are detected by PTi and PTo and shut down:
• Glow discharge
• Arc discharge
• Incandescent mode
Details on the above mentioned EoL cases can be found
in the application guide: "Metal halide lamps" – hints on
application and use"