Motor Control Equipment; Anode Stator Heat Contributions To Housing; Anode Stator Operations For Various Techniques - Varian B-100 Manual De Instrucciones

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1.3

MOTOR CONTROL EQUIPMENT

A. The motor control equipment, whether provided in the X-ray equipment control or separately as a motor starting and
operating device must provide for a means of preventing exposure in case the stator cord is open or incorrectly connected
to its power source.
Stator Drive Frequency
1.4 ANODE STATOR HEAT CONTRIBUTIONS TO HOUSINGS
A. In heavy duty and long time fluoroscopic operation, it is necessary to minimize the heat input to the tube housing
assembly contributed by the stator power as well as the X-ray tube to prevent housing overheat. Three periods of stator
operation must be considered: acceleration of the anode to full speed, maintenance of the anode speed at reduced running
voltage, and braking after exposure. The method of calculating this follows:
WATTS =
E1
I1
t
p.f. =
CAUTION: REMEMBER, THESE WATTS ARE IN ADDITION TO THOSE CONTRIBUTED BY THE X-RAY
TECHNIQUES.
CAUTION: AS THE ANODE ASSEMBLY HEATS UP, RUNNING VOLTAGE MUST BE CONSIDERED IN
ORDER TO INSURE ADEQUATE ROTATIONAL SPEED.
1.5 ANODE STATOR OPERATION FOR VARIOUS TECHNIQUES
A. Radiography
1. When a radiographic exposure is to be made, the stator is energized and the filament voltage boosted during the
time the anode is accelerating to its operational speed. At the end of this time an X-Ray interlock is closed, thus
permitting an exposure to be made either manually or automatically. Also, at this time, the voltage across the stator
is reduced to a value sufficient to maintain operational speed, reducing power input to the housing. This value is
50-60 volts for 50/60 Hz. and 100-110 volts for 150/180 Hz. operation. On 150/180 Hz., the brake circuit is energized
immediately after the exposure. See above.
B. Fluoroscopic Operation
1. Fractional focal spot sizes require anode rotation for fluoroscopic operation, and it is necessary during this type
of operation that the stator be operated at a reduced voltage to limit the stator heat to the housing. A motor
control should be designed to reduce the stator voltage after the operating speed has been obtained to the values
shown in paragraph (A1).
C. Cine Operation
1. Continuous anode rotation is used when Cine operation is being conducted. Use 60 to 300 second holdover when
ever 150/180 Hz. is selected to reduce number of time anode rotation accelerates and deaccelerated through Resonance.
1–4
X-RAY
PRODUCTS
RPM
50 Hz 2800 - 3000
60 Hz 3400 - 3600
150 Hz 8500 - 9000
180 Hz 9500 - 10,800
E1 x I1 x t x p.f.
= Applied stator line voltage (between black and white leads)
= Stator Line amperage for E1
= Time in seconds E1is applied to stator
Power Factor (use 0.83 for this circuit)
X-RAY TUBE ASSEMBLY AND
INSTALLATION MANUAL