The divider provides two ranges that allows it to be used with a variety of readout devices. One mode of operation provides the 1000:1 ratio into a 10 meg ohm load, same as the above GE divider. In this mode, it may be used a a replacement for the GE divider, when connected in a similar manner. It may also be connected to 10 meg ohm input impedance DC digital volt meters or 10 meg 10 X scope probes.
The other range of the divider is 10,000:1, when operated into a 1 meg ohm load, such as the direct input of an oscilloscope.
DC accuracy, when operated into rated load impedance 1%
Divider ratio, switch select able 10,000:1 or 1,000:1
Divider resistance: 100 meg ohm.
Load impedance 1 megohm @10,000:1 or 10 megohm @1,000:1
Voltage range 0 to 150 KVP
DC Accuracy 1% or better 10 to 75 KV per side
Frequency Response DC to 1 kHz +/- 3%, to 100 kHz +/- 5%
Oil filled. May be operated Continuously.
Mechanical: 32 pounds, 10" dia x 12" high, steel can.
HV terminals: Federal Standard 3 pin. 4 pin optional for cathode.
Output terminals: BNC. Oil tight selector switch.
CAUTION: X-Ray equipment operates at lethal voltages. Be sure mains are off before installing this device. Installation must not be performed on energized x-ray equipment.
CAUTION: Insertion of any voltage divider into an x-ray circuit may affect the operation of the x-ray generator. Cathode circuit will tend to decrease the filament current in an x-ray generation due to the addition of contact resistance and cable resistance. When performing final tune up of the generator, remove the cathode leads and restore cathode circuit to normal operating connections.
CAUTION: Do not use high voltage cables longer than 1.5 meter ( 5 feet) as the extra resistance and capacitance may affect the tuning of the generator.
CONNECTION: The voltage divider may be connected near the high voltage transformer or near the x-ray tube. With x-ray generator MAINS OFF, remove x-ray cable from Anode of tube or transformer. Check that there is vapor proofing compound or oil in the receptacles of the voltage divider. This will prevent flash over of the connection. Be sure that all HV plugs and receptacles are clean and free of dirt or metallic particles.
Insert generator Anode cable in receptacle marked ANODE in the 2000 divider. Connect a 1.5 m (5 ft) HV insulated jumper cable from other anode terminal of voltage divider to tube or transformer connector from whence cable was removed. Tighten all nuts to be sure that grounding is not compromised.
Repeat as above for CATHODE cable.
Be certain cables are not interchanged. Mark or tag cables if they may mixed up.
Once HV connections are established, the Mains may be turned on, and generator allowed to warm up.
OSCILLOSCOPE READOUT: Select the 10,000:1 , 1 meg position with the selector switch on top of the divider. Using a pair of 20 foot long RG-59 coaxial cables ( supplied), the output of the voltage divider may be connected to an oscilloscope. Connect the Anode BNC to Channel 1 of the scope, and the Cathode BNC to Channel 2 of the scope. The scale factor of the oscilloscope will be 1 volt = 10KV.
Select 2 volts per division, A+C add mode, and Invert for Ch. 2. A 150 KVP exposure will be 7.5 divisions high. ( 20 KV per division). With lower voltage exposures, such as mammography, a more sensitive 'scope range may be selected.
METER READOUT: Many digital volt meters have a 10 meg ohm input impedance on the DC ranges, such as Fluke model 87. Some meters such as the Fluke 8842A has 10 meg ohm on the 200 and 1000 volt range, and infinite on the lower ranges (20 volts and lower). It is very important to use the correct setting of a DVM or large errors will result.
If using a 10 meg ohm DVM, it is possible to capture the DC voltage of the exposure. Select the 10 meg ohm position on the divider selector switch. The meter scale factor will be 1 volt = 1 kV. Remember that the DVM will read average voltage. This is fine when using three phase or high frequency constant potential generators. Some DVM's have a peak hold feature. Other meters require a sufficiently long exposure to get a reading.
As many mammography generators are single ended, anode only, the output of the anode section of the divider may be connected to the DVM.
If the generator is using anode and cathode, then using BNC adapters, the center lead of the anode may be connected to the positive (+) terminal of the meter, and the cathode output may be connected to the negative (-) terminal. The meter will then be able to read the potential difference (A+C).
(We prefer the use of the oscilloscope!)
There are two major types of special mammography test cables that may be required. Lorad uses a special test cable which looks like a long piece of coaxial cable that has been stripped back, and has a banana plug at one end. This goes into a test well on the generator. An adapter test cable with federal standard on one end and the Lorad cable on the other is part number H44.
Bennett and other manufacturers used the "Alden" style cable. This is a stubby looking plug, with a needle like connector. To loop this through the anode of the voltage divider, a set of adapters is needed. The H45 adapter is an insert into the voltage divider that allows the generator cable to be connected to it. Part number H256-005 P3 is a high voltage cable to complete the circuit back to the tube. It is a five foot cable assembly.
These adaptors may be ordered through GiCi
Storage: It is recommended that freezing temperatures be avoided for this equipment. Maximum accuracy will occur at 70 deg F.
This voltage divider has been designed with the same DC resistance values as the General Electric C1515A and 46-15496681. Those voltage dividers have limited frequency compensation, and following manufacturers direction explicitly have frequency response that is valid to 1000 hZ. The Model 2000 divider was designed as a frequency compensated replacement for those dividers, and is useable at high frequencies, as well as short exposures. With a well characterized rise time, the Model 2000 divider is suitable for use in radiographic, cine, pulsed, and mammographic applications.
This voltage divider should be calibrated annually.