R. E. Beverly III and Associates - Dummy Loads

Dummy Loads

Dummy loads permit testing of pulsed power systems under known load conditions. DL-101 and DL-102 devices are coaxial-cable fed and present a nominal impedance of 50 Ohms to the pulse source. This load impedance is predominantly resistive with a minimum reactive component. The internal construction consists of a stack of ceramic toroidal resistors and hv terminal housed in a polycarbonate tube. This assembly is grounded to the cover using continuous pressure from a spiral-wave spring at the base. Resistor values can be selected to give other dummy-load resistances as shown in the table below. To increase the operating voltage, the surrounding void as well as the resistor stack can be filled with a dielectric medium. A quick-disconnect fitting and purge valve allow filling with the recommended internal dielectric medium. A 2-m (6 foot) length of cable is provided with each load; the load end is fitted with our reentrant connector while the other end is unprepared for interface to the user's pulser. Note that these loads are for single pulse applications only and are not intended for repetitively pulsed usage. The DL-102 load is typically used with our smaller mini-Marx generators.

DL-109 resistors are general-purpose aqueous electrolyte resistors for low-inductance, strip-line applications. These dummy loads are available in two different cylinder heights and dissipate large energies within a very compact volume. The user can quickly change the resistance by adjusting the electrolyte concentration in a distilled-water solution. Stainless-steel electrodes are compatible with environmentally friendly salts such as sodium carbonate and sodium thiosulfate.

Standard Dummy Loads
Model Maximum
Voltage, kV
Resistance,
Ohms
Maximum Pulse
Energy, kJ
Internal Dielectric
Medium
Feed
Type
DL-101 40
120
25-100 1.2 Air
SF6
RG-218/U
DL-102 400 25-100 6.0 Oil RG-218/U
DL-102C 500 35-140 8.4 Oil DS-2134
DL-109-1 25 (55)* 0.3-1000 10 (Electrolyte) Strip Line
DL-109-2 40 (110)* 0.6-1000 25 (Electrolyte) Strip Line
*Operation in an external dielectric medium such as oil or SF6.


Model DL-102C
(8.9 cm diameter x 30 cm height)

Model DL-109-1
(19.5 cm diameter x 8.5 cm height)

Model R-100
(5.08 cm diameter x 13.0, 15.5, 25.5 cm standard lengths)

R-100SS series devices are tubular cartridge-style resistors with integral hydraulic valve to accommodate liquid expansion during pulsed opeation. The polycarbonate tube that defines the internal electrolyte volume is available in various lengths to handle increasing energy dissipation. Although these resistors are standard products, they are available only by special order.

Custom Dummy Loads

Much larger dummy loads utilize our aqueous-electrolyte resistor technology, e.g., the DL-104 system employed with our MV-1 Marx generator. Liquid resistors afford the ability to quickly change resistance by remixing the solution with a different electrolyte concentration. For other applications, custom ceramic resistors may be a better choice, as exemplified by the DL-107 system which utilizes large disk resistors configured as 10 trays with 3 resistors per tray. Trays act as heat sinks and the resistor is cooled by natural air convection. Six control rods, inserted from the bottom of the device, progressively short each section allowing adjustment of resistance.

DL-104 aqueous-electrolyte dummy load:
44-cm pulse line, 17-Ohm line impedance, 6.5-liter
volume, 3-120 Ohm adjustable load resistance
(Na2CO3 solution)
DL-107 adjustable ceramic resistor:
DS-2248 coaxial cable fed, 0.05-0.50 Ohms,
>50 kJ per pulse (shown with cover removed)

Pricing for standard dummy loads may be obtained from the links given on our Sales page. Specifications are subject to change without notice. Inquiries for additional product information are welcome!

Last revision: Wed, 21 Dec 2016 10:04:00 -0500