LOW THERMAL
GUARDED SCANNER
Models: 160B Opt. 3 & 320B Opt.3

Data Proof's Low Thermal Guarded Scanners are designed to improve accuracy in high resistance measurements. Unguarded, the Data Proof scanners have leakages of about  10¹² W which can cause errors of a few tenths of a ppm when measuring 1 MW. Guarding greatly reduces the errors allowing excellent accuracy up to the 10 GW level.

The high guard surrounds the potential and current leads to the high end of each resistor, and a separate low guard surrounds the leads to the low end of the resistor. The guard shields are switched along with the current and potential lines. The guard is carried through shielded cables from the resistor, through the scanner and to the output cables.

The latching relays are modified so that the armatures are included in the guard circuit to prevent leakages through the relay coil circuitry. These are the same relays used to provide  the low thermal performance that Data Proof is famous for.

The Option 3 Scanners are clearly a superior choice for automating precision resistance measurements at higher ranges. they offer advantages for making resistance measurements even if the guard system is not used.The high side and the low side of each resistor are switched by separate relays which reduced leakage currents even when the guard is not used. This 16 four-terminal devices to be connected to the 160B Opt. 3 and  32 four-terminal devices to the 320B Opt.3

     SPECIFICATIONS
Thermoelectric Potentials:
   Less than 20 nanovolts typical
   50 nanovolts maximum
Relay Contact Ratings:
   Life: >10,000,000 cycles at low levels
   Initial contact resistance: 0.05 Ohms maximum
   Current: 100 mA maximum at 10 volts
   Voltage switched: 100 volts max. at 1mA
   Voltage non-switched: 600 volts maximum
Leakage Resistance (guarded):   10¹⁴ Ohms
Leakage Resistance (not guarded): 10¹² Ohms

Data Proof, 2562 Lafayette Street Santa Clara, CA 95050, phone 408 919-1799 fax 408 907-3710, www.dataproof.com