Fluke Biomedical 956A-201-M2 - Manual (Page 5)

1-1
SECTION 1
GENERAL
INFORMATION
1.1 PRODUCT SPECIFICATION
The Victoreen Model 956A-201-M2 Digital Ratemeter, when operated in conjunction with an 897A-2XX
G-M detector, is a single-channel area radiation monitoring system capable of operating over the ranges
of 0.01 to 10
3 mR/h, 0.1 to 10 4 mR/h, or 1 to 10 5 mR/h, depending on the detector selected. The system
monitors gamma radiation over a 5-decade range and provides indication when the radiation level
decreases below a fail threshold, exceeds a warn setpoint, exceeds a high setpoint, or exceeds an over
range setpoint. The over range feature provides two significant benefits. First, it prevents the system
from displaying an on-scale, but inaccurate, reading should the detector become saturated. Second, it
lessens the risk of damaging the detector by disabling it during an overrange condition. Relay outputs are
available to activate alarm annunciators. Analog outputs are available for trend display on a strip chart
recorder or computer. In addition, the monitoring system has an integral check source to verify
operational integrity. The system consists of a Model 897A Series Geiger-Mueller (G-M) Tube Detector
with integral preamplifier and the Model 956A-201-M2 Universal Digital Ratemeter (UDR). A more
detailed description of each piece of equipment can be found in the following paragraphs.
The Model 956A-201-M2 is a modified version of the standard Model 956A-201. The modification
consists of adding the Optional 0-10mV analog output, a “Trip Test” function, and 120 Vac powered,
FAIL and HIGH Alarm outputs (connector P2) to operate a locally mounted alarm.
The 0-10mV analog output is provided by installing the P/N 942-200-95-M1 Dual Analog Output option
circuit board. The 0-10mV output is wired to UDR P6-7/8. The 0-5v output is not used, and is not wired
out to the rear panel.
The “Trip Test” function is provided by replacing the front panel with the P/N 956A-201-20M2 front panel.
The modified front panel adds switch SW5, to actuate the “Trip Test” function. The standard EPROM is
also replaced with P/N 94095605 EPROM. When the “Trip Test” pushbutton is depressed, the alarm
relays will trip, the analog outputs will be driven upscale, the bargraph is driven upscale, the units
backlights are illuminated, the alarm LEDs illuminate, the check source LED illuminates, and the digital
display is forced to display 8.8.8.8.8. Releasing the pushbutton returns all functions except the alarms to
normal. The alarm LEDs and bargraph are returned to normal by pressing the Acknowledge pushbutton.
The 120 Vac powered FAIL and HIGH Alarm outputs (connector P2) are implemented via internal wiring
modifications in the UDR. The FAIL alarm output is obtained by operating the Auxiliary Relay, K1, in
parallel with the normal Fail relay, K3. The HIGH alarm output is obtained from the HIGH alarm relay, K5.
Refer to Modification Sheet 956A-201-M2MS for additional information on the modification.