Ultrahigh-pressure ball mercury-quartz lamps of the DRSh type are powerful, concentrated radiation sources in the visible and ultraviolet parts of the spectrum.

Ultrahigh-pressure mercury lamps with a ball bulb type DRSh 250-3 are intended for use in optical instruments and for laboratory research when powered through special inclusions (lamp power supply DRSh-250-3, remote control PRL-5 and others like that) from an alternating current main with a frequency 50 Hz.

They are used in luminescent microscopes: MLD-1, ML-2, LUMAM R-8 and others.

The lamp of the DRSh 250-3 type is designed to operate on alternating current with a voltage of 127 in series with chokes. During the first 10-15 minutes. after the lamp is turned on, its electrical parameters change (transient mode), and then remain constant (steady state) with a constant voltage.

The DRSh 250-3 lamp is a spherical quartz glass flask into which two diametrically opposite electrodes are sealed at a distance of 3.9-4.5 mm. To facilitate ignition of the lamp, the 3rd ignition electrode is soldered into the ball on the side. The lamp is dosed with a strictly defined amount of mercury and argon. Arc discharge occurs in mercury vapor, generating high brightness.

A schematic diagram of the inclusion of a lamp in an AC network is shown in the figure below.

drsch-250-3 rice 2

D - throttle

L - lamp

K - push button switch

And - an inductor for ignition with a spark length of 15-20 mm

С-1 - capacitor for suppressing radio noise of a lamp with a capacity of 0.05 microfarads at an operating voltage of at least 250 V.

С-2 С-3 - blocking capacitors to limit radio interference of a network with a capacity of 0.5 μF to an operating voltage of at least 250 V

The lamp is ignited using an inductor with a spark length of 15-20 mm, which is switched on with the K button for a short time (no more than 1 min). After the occurrence of an arc discharge between current-carrying electrodes, the inductor is turned off. The wire from the inductor is connected to the base of the ignition electrode.

The normal operating position is vertical, the ignition electrode is on top (the maximum permissible deviation from the vertical position is 10 °). Normal ignition and lamp burning occurs at an ambient temperature of at least + 15 ° C and a voltage of at least 115 V.

Rated power, W - 250

The voltage on the lamp is nominal, in - 72

Rated lamp current, A - 4

Luminous flux not less than lm - 10000

Brightness not less, mnt - 100

Ignition voltage no more, in - 115

Choke voltage:

        in starting mode, at - 127

        in operating mode, in - 93

Amperage:

        in starting mode: 6.5 - 8 A

        in operating mode: 3.8 - 4.2 A

Burning duration not less than h - 300

The average value of the luminous flux and brightness after the average duration of combustion should be at least 80% of their limiting values.

Lamp length no more, mm - 145

The diameter of the flask, mm - 26.5

Lamp height, mm - 40

Lamp weight, g - 27

PRECAUTIONARY MEASURES

The valve body must be earthed and the electrical connections must ensure reliable contact.

The lamp is attached to the legs or socles of the conductive electrodes.

The lamp can operate in a limited volume (casing) provided that the casing dimensions and ventilation conditions are such that the air temperature at a distance of 6 cm from the walls does not exceed 250 C (in steady state). To re-ignite the lamp after it is turned off, it takes no more than (less) 6 minutes.

The ambient temperature should be between 15 and 45 ° C, and the relative humidity should not exceed 70%. Forced cooling in the process of lamp burning is not allowed.

Quartz glass of a bulb of a lamp easily loses its transparency when its surface is contaminated. In view of this, if the flask is contaminated (for example, after touching it with hands, dust on it, etc.), it is necessary to wipe the flask with cotton moistened with alcohol before switching it on.

Personnel working near the lamps and nearby equipment and combustible substances must be protected from hot splinters of the lamp bulb in case of explosion.

When using the lamp, measures must be taken to protect personnel from the effects of powerful ultraviolet radiation from the lamp. In the event of a lamp fight, collect mercury with a rubber bulb and rinse the place where the lamp crashed, rinse with a 1% solution of potassium permanganate. Lamps that fail should be taken out of town and buried in the ground.

Like most gas discharge lamps, DRSh 250-3 lamps, in the absence of appropriate protective devices, can be a source of radio interference. To limit radio interference in the network into which the lamp is switched on, the network blocking should be applied using capacitors with a capacity of 0.5 microfarads.

Lamps like DRSh are intended for work on alternating current with tension 127v for lamps of DRSh 250—3 and 220v for lamps of DRSh of 500 M and DRSh 1000 is consecutive with throttles. Within the first 10 — 15 min. after inclusion of a lamp, its electric parameters change (the unsteady mode), and then remain constants (the set mode) at an invariable tension of a network.