Cropico RBB

A versatile range of resistance Decade Resistance Boxes, available in 5 & 6 decades. Both high accuracy and a wide range, 0.001 ohm to 11 mega ohm, are combined in a rugged case.

The switches used are gold plated to ensure a low contact resistance and negligible thermal E.M.F.

Some models employ the Waidner Wolf technique to eliminate the errors that may be caused by the variations in switch contact resistance. These models are particularly suited to applications such as Pt100 simulation where resolutions as low as 0.001 ohm (» 0.0025°C) are required.

RBB5				RBB6					Decade	Accuracy	Current Max mA
B	C	D	E	B	C	D	E	F
									10 x 0.001Ω	± 2%	2000
									10 x 0.01Ω	± 1%	2000
									10 x 0.1Ω	± 0.5%	2000
									10 x 1Ω	± 0.2%	600
									10 x 10Ω	± 0.05%	200
									10 x 100Ω	± 0.05%	60
									10 x 1kΩ	± 0.05%	20
									10 x 10kΩ	± 0.05%	6
									10 x 100kΩ	± 0.1%	2
									10 x 1MΩ	± 0.1%	0.3

Model	No. Decades	Total Resistance	Resolution	Suitable for Pt100 Simulation	Resolution °C when Simulating Pt100	Residual Resistance Ω
RBB5-B	5	1,112.1Ω	0.01		0.025	1Ω
RBB5-C	5	11,111Ω	0.1	—	—	0.012Ω
RBB5-D	5	111,110Ω	1	—	—	0.012Ω
RBB5-E	5	1.1111MΩ	10	—	—	0.012Ω
RBB5-F	5	11,111Ω	100	—	—	0.012Ω
RBB6-B	6	1,112.11Ω	0.001		0.0025	1Ω
RBB6-C	6	11,112.1Ω	0.01		0.025	1Ω
RBB6-D	6	111,111Ω	0.1	—	—	0.013Ω
RBB6-E	6	1.11111MΩ	1	—	—	0.013Ω
RBB6-F	6	11.1111MΩ	10	—	—	0.013Ω

Calibration

Calibration certificates including UKAS traceable are available on request

Weight

RBB5 - 0.5kg

RBB6 - 0.6kg

Switches

Contact material gold plated brass

Contact resistance = 5 Mega ohm

Insulation Resistance (all paths = 10 giga ohm)

Proof voltage 1kV

Size

350mm x 100mm x 80mm (W H D) approx (all models)

Resistors

Temperature Co-efficient:
±3ppm / +20°C to +85°C ±5ppm maximum over –55°C to + 125°C 0.1, 0.01, and 0.001 dials 10ppm/°C

Full Load Stability:
±35ppm/10,000 hours ±50ppm/26,000 hours

No Load Stability:
±25ppm/10,000 hours ±35ppm/26,000 hours

Over full temperature range:
-50°C to +125°C

Power Rating:
0.33 watt (+85°C) 0.25 watt (+110°C)

Maximum Continuous Working Voltage:
70Vdc / 33vrms

Noise:
Essentially non-measurable <1.5 mV/°C

Thermal E.M.F:
<0.4mV/°C typical

Encapsulation:
Moulded epoxy

Windings:
Exclusive ‘air cushioned’ technique provides virtually stressless elements for improved performance. Non inductively wound. Direction of winding reversed at half turns point