Fluke 956A-201-M2 User Manual

956A-201-M2 & 897A-2XX

Area Monitoring System

Instruction Manual

(Blank page)

CONTENTS

Section 1: GENERAL INFORMATION........................................................ 1-1

1.1 Product Specification ................................................................................... 1-1

1.2 Specifications, G-M Detector, Model 897A Series ....................................... 1-3

1.3 Specifications, G-M Detector Check Source, Model 897A Series................ 1-4

1.4 Specifications, Detector Preamplifier (Integral)............................................ 1-4

1.5 Detector Part Number Description ............................................................... 1-5

1.6 Readout Part Number Description ............................................................... 1-6

1.7 Universal Digital Ratemeter, Model 956A-201-M2....................................... 1-7

1.8 Application ................................................................................................... 1-8

1.9 Specifications Model, 956A-201-M2 ............................................................ 1-9

1.10 Auxiliary Equipment ................................................................................... 1-10

1.11 956A-201-M2 Modifications ....................................................................... 1-11

1.12 Recommended Spares .............................................................................. 1-12

1.13 Receiving Inspection.................................................................................. 1-12

1.14 Storage ...................................................................................................... 1-13

Section 2: OPERATION .............................................................................. 2-1

2.1 Installation.................................................................................................... 2-1

2.2 G-M Detector Mounting................................................................................ 2-1

2.3 G-M Detector Setup..................................................................................... 2-1

2.4 UDR Mounting ............................................................................................. 2-2

2.5 Electrical Interface ....................................................................................... 2-3

2.6 Setup ........................................................................................................... 2-6

Section 3: THEORY OF OPERATION ........................................................ 3-1

3.1 Operation ..................................................................................................... 3-1

3.2 Detector Operation, Model 897A-2XX.......................................................... 3-1

3.3 UDR Operation, Model 956A-201-M2.......................................................... 3-2

3.4 Operational Modes ...................................................................................... 3-4

3.5 Alarms.......................................................................................................... 3-7

3.6 Jumper Selectable Configuration Functions .............................................. 3-10

3.7 Power Up Procedure ................................................................................. 3-12

3.8 UDR Function Switch and Parameter Entry............................................... 3-13

3.9 Setpoint Descriptions................................................................................. 3-15

3.10 Setpoint Error Codes ................................................................................. 3-16

3.11 Analog Output............................................................................................ 3-17

3.12 Software Calculations ................................................................................ 3-18

3.13 Functional Description, Model 897A G-M Detector.................................... 3-19

3.14 Functional Description Universal Digital Ratemeter (URD), Model 956A-

201............................................................................................................. 3-21

i

Section 4: MAINTENANCE AND CALIBRATION....................................... 4-1

4.1 Maintenance ................................................................................................ 4-1

4.2 Calibration.................................................................................................... 4-1

4.3 Calibration/Electronic Adjustment ................................................................ 4-1

4.4 955A System Field Calibration..................................................................... 4-3

4.5 Detector Calibration ..................................................................................... 4-5

Section 5: TROUBLESHOOTING ............................................................... 5-1

5.1 Troubleshooting ........................................................................................... 5-1

5.2 HV Power Supply Adjustment...................................................................... 5-7

Appendix A: CONNECTOR DESIGNATIONS ................................................A-1

A.1 Connector Designations............................................................................... A-1

Appendix B: APPLICABLE DRAWINGS........................................................B-1

B.1 Applicable Drawings ....................................................................................B-1

Appendix C: BILL OF MATERIALS................................................................C-1

C.1 Bill of Materials ............................................................................................C-1

Appendix D: COAXIAL CABLE TERMINATION INSTRUCTIONS ................ D-1

D.1 Coaxial Cable Termination Instructions ....................................................... D-1

Appendix E: SUPPLEMENTAL DATA (CUSTOMER SPECIFIC).................. E-1

E.1 Supplemental Data (Customer Specific) ...................................................... E-1

ii

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
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.

3

mR/h, 0.1 to 104 mR/h, or 1 to 105 mR/h, depending on the detector selected. The system

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.

1-1

The Model 956A-201 Series Readout and 897A Series G-M detectors have been successfully subjected
to seismic and environmental qualification testing per IEEE 344-1975 and IEEE-323-1983. In addition,
EMI/RFI testing per the requirements of EPRI TR-102323-R1, MIL-STD-461D, and EN 61000-6-1:2001
has also been successfully performed. Please consult the factory for specific details of the qualification
testing program.

The 956A-201-M2 operation described herein is based on the use of EPROM P/N 94095605, Rev. 1.

Geiger-Mueller Detector, Model 897A-Series

Victoreen 897A-Series G-M detectors use a thin walled Geiger-Mueller tube to detect ionizing radiation.
Each 897A-Series detector has a G-M tube, a check source, and a preamplifier. The check source is a
low-level radioactive source actuated by a + 15 Vdc meter movement. The preamplifier provides the
pulse conditioning and cable driving capability necessary to drive a Victoreen 956A-201 Series digital
ratemeter.

All 897A-Series detectors are functionally identical. They differ only in housing material, tube type, and
range. The 897A Series detectors operate in the voltage range of 500 - 650 Vdc. An example of the
detector plateau, based on different high voltages, is located in Figure 1-1. Refer to the specifications for
all 897A-Series G-M detectors for further information.

NOTE

The 897A Series G-M detectors contain an eight-microcurie 36CI

check source. Nuclear Regulatory Commission regulations
define this source as an exempt quantity.

Application

The Model 897A G-M Detector is designed to operate with the Victoreen Model 956A-201 Universal
Digital Ratemeter (UDR) or with other Victoreen readouts. Each detector measures a five-decade range.
Three measurement ranges are available: low, medium, and high. The low range covers 0.01 to 10
mR/h, the medium covers 0.1 to 10

4

mR/h, and the high covers 1 to 105 mR/h. The Model 897A detector
may also be used with the Victoreen Model 960 Digital Radiation Monitoring System equipment or the
Victoreen Model 856 Analog Readout.

3

1-2

1.2 SPECIFICATIONS, G-M DETECTOR, MODEL 897A SERIES

Dimensions (Approximate 7 1/8 x 3 inches (18.1 x 7.6 cm)
Weight (Approximate) 2.5 lbs.
Housing Material
897A-210, 897A-220, 897A-230
897A-211, 897A-221, 897A-231
Fill Gas:
897A-210, 897A-211
897A-220, 897A-221
897A-230, 897A-231
G-M Tube Wall Thickness:
897A-210, 897A-211
897A-220, 897A-221
897A-230, 897A-231
Mounting Wall mount
Mating Connectors 897A-2x0:

Required Cable P/N 50-100 or substitute with two coaxial

External Pressure Limit 30 psig
Storage Temperature -10° to 122°F (-23° to 50°C)
Operating Temperature -10° to 122°F (-23° to 50°C)
Relative Humidity 0 to 95% non-condensing
Operating Voltage 500 – 650 Vdc (supplied by digital ratemeter)
Plateau Length 100 – 150 Vdc
Plateau Slope:
897A-210, 897A-211
897A-220, 897A-221
897A-230, 897A-231
Dead Time (Approximate)
897A-210, 897A-211
897A-220, 897A-221
897A-230, 897A-231
Detector Element Life Exceeds 1000 hours at full-scale
Energy Dependence of Reading +/- 15% from 80 keV to 1.5 MeV
Detector Accuracy ± 20% of actual dose for Cs-137
Radiation Detected Gamma rays, X-rays

Aluminum, weatherproof
Stainless Steel, weatherproof

Neon/Argon/Halogen
Helium/Neon/Halogen
Helium/Neon/Halogen

40 mg/cm
80 mg/cm

2

2

80 mg/cm2

92-7005-17A, 12 Pin Female
92-7005-12A, Bushing
92-7005-9A, Clamp

897A-2x1 (stainless steel):
92-7005-15A, 12 Pin Female (stainless steel)
92-7005-12A, Bushing
92-7005-13A, Bushing

conductors, two twisted pairs, and overall shield.

0.1%/V

0.2%V

0.3%V

45 microseconds
28 microseconds
20 microseconds

1-3

1.3 SPECIFICATIONS, G-M DETECTOR CHECK SOURCE,

MODEL 897A SERIES

Radionuclide
Source Activity: 8 microcuries
Scale Reading (Approximate)
897A-210, 897A-211
897A-220, 897A-221
897A-230, 897A-231
Voltage 12 – 15 Vdc
Encapsulation Brass, high temperature soldered

36

CI

10-150 mR/h, Typical
10-50 mR/h, Typical
10-50 mR/h, Typical

1.4 SPECIFICATION, DETECTOR PREAMPLIFIER

(INTERGRAL)

Input Impedance >100 k-ohms
Output Impedance 50 ohms
Output Pulse Polarity Positive
Output Signal (50 ohm terminated) + 5 Vdc square-wave
Low Voltage* + 15 Vdc (Optional + 10 Vdc is Jumper Selectable)
Power Requirements + 15 Vdc @ 120 mA
Maximum Cable Length 2000 feet
Electronic Exposure Life Approximately 105 rads
Discriminator Level Adjustable from 0 to 1.5 Vdc (nominal value =1.00

Vdc)
Anti-Jam Level Adjustable from 0 to + 3 Vdc
Anti-Jam Oscillator Frequency Approximately 50 kHz
Pre-divide* Jumper Selectable
Analog & Digital Monitor Configuration Divide by 2, Square wave output
Optional Monitor Configuration Raw pulse output

* Preamplifier low voltage and pre-divide are selected with jumpers. Refer to the preamplifier circuit

description for more information. Standard Configuration is +15 Vdc Divide by 2.

1-4

1.5 DETECTOR PART NUMBER DESCRIPTION

897A-2 XY

2 = High reliability components for Class 1E service

PRODUCT SERIES
897 = Sr-90 check source (NRC license required) with a

Y = 0, Aluminum Housing
Y = 1, Stainless Steel Housing

X = 1, 0.01 mR/h – 1E3 mR/h
X = 2, 0.10 mR/h – 1E4 mR/h
X = 3, 1.00 mR/h – 1E5 mR/h

120 VAC solenoid actuator. No longer manufactured.

897A = CI-36 check source (exempt quantity) with + 15
VDC meter movement actuator.

1-5

1.6 READOUT PART NUMBER DESCRIPTION

956A-20X-MX

2 = High reliability components for Class 1E service

PRODUCT SERIES
956 = 16k x 8 PROM, 8k x 8 RAM; 128 bytes EEPROM; V-Channel front

Blank = Standard Unit
M = Special Options/Modifications
MX = Special Modification (X = Modification Number)
M2 = Add 942-200-95-MI Dual Analog Output Circuit Board, Trip Test

Function, and Externally Powered Fail and High Alarm Relay

Contacts
00 = 120 Vac Check Source Mechanical (Discontinued 9/95)
01 = 15 Vdc Check Source Mechanical (current product configuration)
0X = Future Variations

panel – No longer manufactured
956A = 32k x 8 PROM, 8k x 8 RAM, 256 bytes EEPROM; flat front panel –

revised rear panel pinouts.

Figure 1-1 Detector Plateau (typical)

1-6

1.7 UNIVERSAL DIGITAL RATEMETER, MODEL 956A-201-M2

The Victoreen Model 956A-201-M2 is a modified version of the Model 956A-201 Universal Digital
Ratemeter (UDR), when connected to a Victoreen Model 897A-2XY Geiger-Mueller (G-M) tube detector,
comprises a monitoring system that operates over a five-decade range. The UDR provides display,
control, and annunciation functions for the monitoring system, and will display readings in the range of

0.01 to 10

Standard features for the instrument consist of a three-digit display of the radiation value, in units of
mR/h, R/h, or kR/h, and a multi-colored bargraph indicator that covers the entire range of the UDR. The
bargraph will change color in the event of an alarm condition (green for normal, amber for warning, and
red for high). Front panel alarm indicators and rear panel relay outputs for alarm annunciation are also
included. Front panel pushbuttons are provided to apply power, display alarm limit setpoints,
acknowledge alarms, and to activate the check source. In addition, the 956A-201-M2 is provided with a
front panel mounted TEST pushbutton, that performs a self-test of the UDR.

Analog outputs of 0 - 10 Vdc (1) and 4 - 20 mA (2) are provided for recording and computer monitoring.
The outputs may also be used to drive a remote meter or a local (i.e. near the detector) indicator.

In addition, the 956A-201-M2 is provided with the P/N 942-100-95-M1 dual analog output option circuit
board that provides a 0-10 mV dc analog output.

The 956A-201-M2 also included an internal wiring modification that applies 120 Vac to the Fail and Alarm
relay contacts. The auxiliary relay, K1, is hard wired to operate in parallel with the Fail relay to supply AC
power to a local alarm. AC power is supplied from rear panel connector P1 to detector connector P2.

Refer to Modification Sheet 956A-201-M2MS for additional information on the modification.

5

mR/h. Refer to Figure 1-2 for view of the 956A-201-M2 front panel.

All electronics required to interface with the VICTOREEN 897A Series G-M detector are included within
the 956A-201 UDR. The electronics consist of a high voltage power supply, low voltage DC power supply
and the hardware/software required for UDR operation. The system also includes an overrange indicator
to preclude the possibility of on-scale readings when the radiation field is beyond the range of the
detector.

The following paragraphs describe the available options. A separate manual for each option board is
available with more detailed information. Listed below are the option boards currently available.

1. 942-200-75: ANALOG INPUT OPTION BOARD - (Generally not used for normal operation with the
956A-201 UDR, however, it is used if the UDR is part of a simulator) Contains four (4) separate
channels for analog inputs. A 0 to 10 Vdc input or 4 to 20 mA input can be selected independently for
each channel using the jumpers and switches provided on the board. Possible inputs to the board
include: temperature, pressure, flow, or simulated radiation.

2. 942-200-80: COMMUNICATIONS LOOP OPTION BOARD - Designed to enable a EIA RS232C
standard communications link between VICTOREEN's ratemeter and a user computer system or CRT
terminal, with baud rates ranging from 50 to 19200 baud. An asynchronous communication interface
adapter is utilized to format the data and control the interface.

The VICTOREEN Communication Loop Option Board also provides an isolated multi-drop, serial

communications port for interface with a supervisory computer system. The serial data is in a
modified RS-232 format, and utilizes Victoreen's proprietary VICO loop protocol. For maximum
external noise protection, a six-conductor communications cable is used.

1-7

3. 942-200-95: ANALOG OUTPUT BOARD - Designed to provide a user selectable single output
voltage of: 0 - 10 Vdc, 0 - 5 Vdc, 0 - 1 Vdc, 0 - 500 mVdc, 0 - 100 mVdc, 0 - 50 mVdc, or 0 - 10
mVdc.

4. 942-200-95M1: DUAL ANALOG OUTPUT BOARD - Designed to provide two user selectable output
voltages. Output #1 is either 0 - 5 Vdc, or 0 - 10 Vdc, while output #2 is either 0 - 10 mVdc, 0 - 50
mVdc, 0 - 100 mVdc, 0 - 500 mVdc, or 0 - 1 Vdc included in the 956A-201-M2.

5. S157033A2 Line Filter/Surge Suppressor Assembly Designed to provide EMI/RFI protection for two
956A Series digital ratemeters and 897A Series G-M detectors. The assembly consists of two (2)
separate and independent line conditioning circuits that provide filtered AC power to each 956A
Series ratemeter. The S157033A2 is designed to mount in the center section of the 948B-1A-5 dual
module rack chassis, to provide EMI/RFI protection for two (2) 956A Series ratemeters. The major
active components of the S157033A2 are two (2), 960SS-200 Surge suppressor circuit boards, two
(2), 92-9015-A Line Filters, and two (2) 14-235 ferrite cubes. The S157033A2 also contains AC line
and neutral fuses to protect the internal circuitry from over current conditions.

To meet the requirements of EPRI TR-102323-R1, for radiated fields above 80MHz, the low

discriminator in the detector preamplifier must be set to 1.0 volts. This setting has been incorporated
into the factory calibration of all 897A Series G-M detectors.

1.8 APPLICATION

The Model 956A-201-M2 UDR is used with all Victoreen 897A Series G-M Detectors. The detector
specific setpoints for the 956A-201-M2 UDR are configured by the user for the range of the particular
detector supplied. The detector/preamp, when connected to a UDR, will function as a single channel
digital area monitoring system. For additional information on various applications, please contact
Cardinal Health, Radiation Management Services Applications Engineering Group.

1-8

1.9 SPECIFICATIONS MODEL, 956A-201-M2

General specifications for the 956A-201-M2 UDR are listed below. The 956A-201-M2 is designed for
nuclear applications, and any repairs to it by personnel not qualified may void the nuclear rating. If a
problem develops, the UDR can either be returned to the factory for service or repaired by a qualified
technician.

Main Display

Bargraph Display
(Dynamic Range)

Alarm Indicators

Display Selection (Momentary Pushbuttons)

Check Source

Alarm Ack.

Power ON/OFF
Relay Outputs
(Fail-safe operation)

High Voltage Output
Detector Check Source Power
Analog Outputs

Remote Alarm Ack Input

Seven segment – three digits with backlighted
radiation units display, floating decimal point and
exponential setpoint entry
Three segments per decade, .01 to 10
segments) (green for norm, amber for warn, and red
for high)

HIGH Alarm (Red LED) – Flashing until acknowledged
WARN Alarm (Amber LED) – Flashing until

acknowledged
FAIL Alarm (Red LED) – Does not flash, automatically
resets
RANGE Alarm (Red LED), overrange/underrange –
Does not flash, automatically resets
HIGH, High Alarm Setpoint
WARN, Warn Alarm Setpoint
TEST, Initiates Trip Test Function (956A-201-M2)
Activates radioactive Check source and associated
green LED indicator. Momentary, non-latching
pushbutton operation
Alarm acknowledgment causes alarm indicators to go
to a steady on state after acknowledgment. Relays
will reset when radiation level drops below setpoint.
Internal jumper causes alarms to be reset
automatically when radiation level drops below
setpoint (no operator input required).
Alternate action pushbutton for AC power.
HIGH Alarm – DPDT rated 5 A @ 120 Vac (one set
120 Vac powered for use with optional local alarm)

WARN Alarm – DPDT rated 5 A @ 120 Vac
FAIL Alarm – DPDT rated 5 A @ 120 Vac
AUX (Fail) – DPDT rated 5 A @ 120 Vac (956A-201-

M2)
DC rating for all relays is 5 A @ 29 Vdc
NOTE: 120 Vac has been internally wired to the
Alarm, and AUX relay contacts, connector P2. Refer
to Loop Diagram S174014C-102.
300 Vdc – 1800 Vdc @ 0.4 mA
+15 Vdc @ 20 mA

4 to 20 mA (2) (500 Ω load each, max.) and 0 to 10
Vdc (1 KΩ load min.), logarithmic. May be scaled for
any one decade (minimum) or to the full range of the
detector (maximum).
0 to 10 mV (1 KΩ load min) is available from the 942­200-95-M1 Analog Output Option Board (956A-201­M2).
Optically isolated DC input

6

mR/h (24

1-9

Detector Input

UDR Electronic Accuracy

Dimensions (H x W x D)
Weight
Power
Operating Temperature
Relative Humidity
Compatible Detector
Heat Loading

Digital Pulse, Up to 2000 feet from UDR, 50 ohm input
impedance

± 1 digit (± 1% of the displayed value, exclusive of the
detector energy response

3.5 in. x 5.6 in. x 13.5 in. (8.9 cm x 14.2 cm x 34.3 cm)
Approximately 3.7 lb. (1.67 kg)
120 Vac ± 10%, 50/60 Hz, 28 watts (240 Vac optional)
32°F to 122°F (0°C to + 50°C)
0 to 99% non-condensing
897A Series, G-M (Geiger Mueller tube)
Approximately 96 BTU/hr

1.10 AUXILIARY EQUIPMENT

Auxiliary Equipment

Model Description

Model 848-8 Field Calibrator (100 mCi)
Model 848-8A Field Calibrator (10 mCi)
Model 848-8B Field Calibrator (20 mCi)
Model 848-8-105 897A Adapter (all types)
Model 848-8-400 897A Stainless Steel Detector Adapter, 897A-

2x1
Model 942TS UDR Test Set
Model 958A-40 Local Alarm, without meter
Model 958A-10, -20, -30 Local Alarm, with meter
Model 948-1 Rack Chassis, 3 Channel
Model 948A-2 Blank Panel
Model 948-3 Table Top Enclosure
Model 948-10 Panel Adapter
Model 50-100 Interconnecting Cable
Model S157033A2 Line Filter/Surge Suppressor
Model 948B-1A-5 Dual Channel Rack Chassis

1-10

Figure 1-2. Front Panel, Model 956A-201-M2 Universal Digital Ratemeter (not to scale)

Figure 1-3. Rear Panel, Model 956A-201-M2, Universal Digital Ratemeter (not to scale)

1.11 956A-201-M2 MODIFICATIONS

Refer to Modification Sheet 956A-201-M2 for a complete description of the modification performed on this
unit.

1-11

1.12 RECOMMENDED SPARES

Table 1-2 lists the recommended spare parts for the 955A Radiation Monitoring System.

Table 1-2. Recommended Spare Parts List

897A Detector

Part Number Description Used On

46-77 “O”-Ring, Detector Housing 897A-2X0
857-211-15 Gasket, Detector Housing 897A-2X1
857-211-19 Mounting Strap 897A-2X1
857-211-18 Detector Mounting Bracket 897A-2X1

956A-201 UDR

Part Number Description Used On

92-7027-1A Fuse F2, 2 Amp, main AC power All
19-62 Fuse F1, 50 mA, anti-jam circuit All
92-9042-A Jumper Block (10 required) All
942-200-50 Power Supply All
82-73-1 Relay All

1.13 RECEIVING INSPECTION

Upon receipt of the unit:

1. Inspect the carton(s) and contents for damage. If damage is evident, file a claim with the carrier and
notify the Cardinal Health, Radiation Management Services Customer Service Department.

Cardinal Health, Radiation Management Services

6045 Cochran Rd.

Cleveland, Ohio 44139

Phone: [phone], Fax: [phone]

2. Remove the contents from the packing material.

3. Verify that all items listed on the packing list have been received and are in good condition.

If any of the listed items are missing or damaged, notify the

Cardinal Health, Radiation Management Services Customer
Service Department.

NOTE

1-12

1.14 STORAGE

Instruments storage must comply with Level B storage requirements as outlined in ANSI N45.2.2 (1972)
Section 6.1.2(.2). The storage area shall comply with ANSI N45.2.2 (1972) Section 6.2 Storage Area,
Paragraphs 6.2.1 through 6.2.5. Housekeeping shall conform to ANSI N45.2.3 (1972).

Level B components shall be stored within a fire resistant, tear resistant, weather tight enclosure, in a
well-ventilated building or equivalent.

Instruments storage must comply with the following:

1. Inspection and examination of items in storage must be in accordance with ANSI N45.2.2 (1972)
Section 6.4.1.

2. Requirements for proper storage must be documented and written procedures or instructions must be
established.

3. In the event of fire, post-fire evaluation must be in accordance with ANSI N45.2.2 (1972), Section

6.4.3.

4. Removal of items from storage must be in accordance with ANSI N45.2.2 (1972), Sections 6.5 and

1-13

(Blank page)

Section 2

OPERATION

2.1 INSTALLATION

Installation consists of selecting suitable mounting sites for the detector and ratemeter, mounting the
equipment, making the required electrical connections, and entering the desired setpoints. Installation
drawings are provided in Appendix B of this manual.

Remove all power prior to installing the UDR or detector.

CAUTION

2.2 G-M DETECTOR MOUNTING

The 897A Series G-M detectors can be mounted to any suitable structure e.g. a wall or post, using the
mounting bracket (P/N 843-6-26) included with the detector. The maximum distance between the
detector and ratemeter is 2000 feet (610 meters). The detector should be mounted above normal head
height with the detector connector facing away from the area being monitored. For additional information
refer to the applicable engineering drawings, provided in Appendix B, for detector mounting dimensions.

To protect the monitor from EMI/RFI transients, the detector must be earth grounded through its wall­mounting bracket.

2.3 G-M DETECTOR SETUP

The low voltage power supply input for the preamplifier is jumper selectable. This allows the use of either
a +10 Vdc or +15 Vdc supply for detector power. If the detector is used with a 956A-201 Series UDR, the
standard +15 Vdc position is used. If the detector is used in an analog radiation monitoring system, the
+10 Vdc position is used. Jumper configurations are listed in Table 2-1.

Table 2-1 Input Voltage Jumper Position

Jumper Position Input Voltage

J3 AB + 15 Vdc (factory set), digital readout
J3 BC + 10 Vdc, analog readout

The G-M tube output pulse is conditioned with a divide by 2 pulse shaping circuit to transmit a square
wave from the detector. The conditioning also permits use of the detector with analog readouts, using a
diode pump counting circuit. For use with fast rise time scalers, a jumper is provided to output the
detector pulse directly. Jumper configurations are listed in Table 2-2.

2-1

Table 2-2 Divide Options Jumper Position

Jumper Position Divide Option

J1, J2 AB 2, square wave output (factory set)
J1, J2 BC 1, direct coupled

2.4 UDR MOUNTING

The UDR is a self-contained unit that can be mounted in four different ways.

When installing the UDR in enclosed panels or cabinets, ensure
that the maximum operating temperature (122° F) is not exceeded.
The total heat load should be calculated to determine whether
cooling by natural convection or forced ventilation (i.e. fans) is
required. The heat load for a single UDR is approximately 96
BTU/hr.

CAUTION

Where more than four units are to be mounted in a cabinet, it is

recommended that the center position in each chassis be left blank
to facilitate the flow of cooling air through the cabinet.

For seismic applications, the rear of the chassis must be

supported, or the sides of the chassis must be fastened
together. For further information, contact Cardinal Health,
Radiation Management Services.

To protect the monitor from EMI/RMI transients, the Rack

Chassis must be connected to an earth ground.

1. The first mounting utilizes a 19-inch rack chassis adapter, Victoreen Model 948-1. This configuration
requires 3.5 inches of rack height and can be used to mount up to three UDRs side by side. A blank
filler panel, Victoreen Model 948A-2, is available to cover unused mounting positions. Refer to
drawing GEL-948-1 for mounting dimensions.

Where EMI/RFI compliance is required, the Model 948B-1A-5 Dual Channel rack chassis is
available. The Model 948B-1A-5 is designed to accept two Model 956A UDR’s, mounted in the left
and right side positions. The center position is used to mount a Model S157033A2 Line Filter/Surge
Suppressor Assembly. AC power for each channel is routed to the surge suppressor, which then
feeds the AC power to the 956A UDR’s. Refer to GEL-948B-1A for mounting dimensions.

NOTE

NOTE

NOTE

2. The second mounting consists of a single channel tabletop enclosure, Victoreen Model 948-3.
Dimensions for the enclosure are 4.5 inches high by 6.8 inches wide by 14.9 inches deep. Refer to
drawing 948-3-5 for mounting dimensions.

3. The third mounting consists of a panel mount enclosure, Victoreen Model 948-9. Cutout dimensions
for this enclosure are 3.75 inches high by 6.45 inches wide; the outside dimensions for the enclosure
are 4.0 inches high by 6.7 inches wide by 13.7 inches deep. Refer to drawing 948-9-5 for mounting
dimensions.

2-2

4. The fourth mounting utilizes the Victoreen Model 948-10 Rack Chassis Adapter to mount a 956A
UDR into an existing Victoreen analog ratemeter rack chassis such as those used for the Victoreen
842 series analog ratemeter. Refer to drawing GEL-948-10 for mounting dimensions.

The UDR is simply inserted into the selected mounting enclosure and secured using the front panel pawl
fastener.

2.5 ELECTRICAL INTERFACE

Ensure all power is off prior to connecting the field wiring

Electrical interconnections at the detector are made via the mating "MS" style connector supplied with the
detector and loop drawing S174014A-102.

Electrical interconnections to the UDR are implemented with the mating connector kit, P/N 942A-100- 4
(supplied with the readout) by using the connector input/output assignments provided in Tables 2-3
through 2-10, and loop drawing S174014A-102, provided in Appendix B. Termination instructions for
coaxial connections can be found in Appendix D. A service loop of a minimum of 12 to 16 inches should
be provided to permit partial withdrawal of the UDR for setpoint adjustment and troubleshooting.

Connector pins should be soldered to the cable using 60/40-tin/lead resin core solder and a soldering iron
of 50 watts or less.

To protect the monitor from EMI/RFI transients, the mounting chassis must be earth grounded.

Table 2-3. Rear Panel Connections

Connector Function

P1 Relay/Output, Remote Alarm Acknowledge
P2 Detector Connector
P3 AC Power Input
P4 Detector High Voltage (SHV)
P5 Detector Signal Input (BNC)
P6 Auxiliary outputs 0 – 10 Vdc & 4 – 20 mA DC
P7 RS232C, Optional

WARNING

2-3

Table 2-4. Connector P1 – Input/Output, 956A-201-M2

Pin Signal Internal Connection

1 120 Vac Line Relay Board K1-A/V2
2 120 Vac Neutral P2-13
3 120 Vac Ground P2-11
4 Spare Relay Board K1-D
5 Spare Relay Board K1-F
6 Spare Relay Board K1-E

7 Fail Relay, Common Relay Board K3-A
8 Fail Relay, n.o. Relay Board K3-B

9 Fail Relay, n.c. Relay Board K3-C
10 Fail Relay, Common Relay Board K3-D
11 Fail Relay, n.o. Relay Board K3-F
12 Fail Relay, n.c. Relay Board K3-E

13 Warn Relay, Common Relay Board K4-A
14 Warn Relay, n.o. Relay Board K4-B
15 Warn Relay, n.c. Relay Board K4-C
16 Warn Relay, Common Relay Board K4-D
17 Warn Relay, n.o. Relay Board K4-F
18 Warn Relay, n.c. Relay Board K4-E

19 Alarm Relay, Common Relay Board K5-A
20 Alarm Relay, n.o. Relay Board K5-B
21 Alarm Relay, n.c. Relay Board K5-C

22 Spare Not Used
23 Spare Not Used
24 Spare Not Used

25 + Remote Acknowledge Main Circuit Board J9-1
26 - Remote Acknowledge Main Circuit Board J9-2

27 - 37 Spare Not Used

n.o. = normally open, n.c. = normally closed, Relays shown in shelf, or de-energized state.

Table 2-5. Connector P2 – Detector Connector, 956A-201-M2

Pin Signal Internal Connection

1 Detector + 15 Vdc Supply Power Supply + 15 Vdc

2 Not Used Power Supply – 15 Vdc

3 Supply Ground Power Supply Ground

4 + 15 V C/S On Relay K2

5 - 15 V C/S Off Relay K2

6 Not Used -

7 Not Used -

8 Not Used -

9 DC Ground Main Circuit Board J5-9
10 0 – 10 Vdc, Remote Meter Main Circuit Board J5-10
11 AC Ground P1-3 AC Ground
12 Fail, N.C (Switched, 120 Vac, Line) Relay Board K1-C (L)
13 120 Vac (Neutral) P1-2, 120 Vac (N)
14 Alarm N.C (Switched, 120 Vac, Line) Relay Board K5-E (L)

0 – 10 Vdc selected for Remote Meter use on P2 (10, 11) not P6 (5, 6).

2-4

Table 2-6. Connector P3 – Power Input

Pin Signal Internal Connection

1 120 Vac, Line Line fuse (F2)

2 120 Vac, Neutral Power Supply, 120 Vac (n)

3 Safety Ground Chassis

Table 2-7. Connector P4 – Detector High Voltage

Pin Signal Internal Connection

MHV Detector High Voltage Direct

Table 2-8. Connector P5 – Detector Signal Input

Pin Signal Internal Connection

BNC Detector Signal Direct

Table 2-9. Connector P6 – Auxiliary I/O, 956A-201-M2

Pin Signal

1 4 – 20 mA Output #1 (+)

2 4 – 20 mA Ground (-)

3 4 – 20 mA Output #2 (+)

4 4 – 20 mA Ground (-)

5 0 – 10 V* (+)

6 Ground (-)

7 Analog Output Option (+), 0-10 mV

8 Ground (-)

9 through 24 Not used

*0 – 10 Vdc selected for Remote Meter use on P2 (10, 11) and is not available on P6 (5, 6).

Table 2-10. Connector P7 – RS232C Option

Pin Signal

1 Protective Ground

2 Transmit Data

3 Receive Data

4 Request to Send (RTS)

5 Clear to Send (CTS)

6 Data Set Ready (DSR)

7 Signal Ground

8 Receive Line Signal Detect (DCD)
20 Data Terminal Ready

Table 2-11. 897A Detector Connection

Pin Signal

K Protective Ground

H Check Source

J Check Source

E High Voltage

MTG Screw Chassis Ground

C + Voltage In
G Signal Output

2-5

2.6 SETUP

Table 2-12 summarizes the jumper selectable configuration options. To place the system in operation,
the following steps should be performed:

Ensure you have read and fully understand Section 3 prior

to continuing.

1. Verify that jumpers and DIP switches, on the UDR and detector, are set for the operational features
desired. Refer to Section 3, Table 3-2. The 897A Detector jumpers are preset at the factory per
Tables 2-1 and 2-2, and should not be changed.

2. Apply power to the unit. The bargraph will illuminate momentarily followed with a momentary
actuation of the digital value display. The unit will then begin to display the ambient radiation at the
detector location.

The default setpoints in the UDR memory are for an 897 A-220
detector (1.00E-1 mR/h to 1.00E4 mR/h); verify the appropriate
setpoints for the actual detector are entered per Section 3
(Parameter Entry).

NOTE

NOTE

Calibration constant and detector deadtime value are obtained
from the factory calibration data sheet for each detector.

3. Detector dependent setpoints such as analog outputs, High/Low scale values, Range, Underrange,
Overrange limit, calibration constant, and detector deadtime may now be verified and if required,
modified using the procedures outlined in Section 3.

4. Channel dependent setpoints such as alarm limits may be verified, and if required, modified using the
procedures outlined in Section 3.

5. Electronic adjustments affecting calibration are factory set and should not be readjusted for initial
operation unless the UDR has been in storage for more than one year. If the Unit has been in
storage for more than one year, the electronic calibration described in Section 4 should be performed.

NOTE

2-6

Table 2-12. Model 956A-201-M2 Option Jumpers

Jumper Function Position Operation

JP1 Microprocessor Reset Out

In

JP2 PROM Type 1-2

2-3

JP3-1/JP3-2 Statistical Accuracy (Note: This

accuracy refers only to the
statistical interpretation of
detector counts, and not

Out/Out
Out/In
In/Out
In/In

Normal Operation (factory) Momentary
connect to reset microprocessor without
cycling AC power
Not Applicable
PROM 27128
PROM 27256 (factory)
2% Accuracy – Not Implemented
5% Accuracy – Not Implemented
10% Accuracy – Not Implemented
Fixed one second display update (factory

detector accuracy)

JP3-3 Alarm Acknowledge In

Out

JP3-4 Fail Alarm In

Out

JP3-5 Check Source Alarm In

Out

JP4 Shield Polarity Selection 1-2

2-3

Manual Acknowledge (factory)
Automatic
Enable No Counts Fail Alarm (factory)
Inhibit No Counts Fail Alarm
Alarm Inhibited (factory)
Alarm Enabled
Negative Input Pulse (Other Detectors)
Positive Input Pulse (G-M Detectors)
(factory)

JP5 Shield Polarity Selection 1-2

2-3

JP-6 Anti-Jam Fuse Selection 1-2

2-3

JP7 Detector Type for Anti-Jam

Circuit Timing

1-2
2-3
Out

Shield for Negative Pulse
Shield for Positive Pulse (G-M) (factory)
Enable for Normal Operation (factory)
Anti-Jam Circuit fuse bypassed (testing)
Scintillation
G-M Tube (factory)
Anti-Jam Circuit Disabled (for testing only)

2-7

(Blank page)

Section 3

THEORY OF

OPERATION

3.1 OPERATION

This section describes the operation and set up of a Digital Area Monitoring System. The system consists
of a Model 956A-201-M2 UDR and a Model 897A Series G-M Detector. The detector preamplifier
provides the electronics interface between the detector and the UDR. The preamplifier provides input
pulse discrimination, pre-divide capability, anti-jam circuitry, pulse amplification and output drive
capabilities. The output of the preamplifier is transmitted to the UDR. The 956A-201-M2 UDR uses this
information to generate the dose rate display, error codes, alarms, and analog outputs.

Operation of the 956A-201-M2 UDR consists of operator functions and configuration functions. All
operator functions are performed using the front panel shown in Figure 1-2. Configuration functions are
performed using internal switches and/or jumpers, which are accessible with partial removal of the UDR
from the mounting enclosure. Calibration involving trim pots is described in Section 4.

For applications where EMI/RFI compliance is required, the S157033A2 Line Filter/Surge Suppressor
Assembly, designed to provide EMI/RFI protection for the 956A Series digital ratemeter and 897A Series
G-M detectors, is available. The assembly consists of two (2) separate and independent line conditioning
circuits that provide filtered AC power to each 956A Series ratemeter. The S157033A2 is designed to
mount in the center section of the 948B-1A-5 dual module rack chassis, to provide EMI/RFI protection for
two (2) 956A Series ratemeters.

3.2 DETECTOR OPERATION, MODEL 897A-2XX

The Digital Area Monitor uses a Model 897A-2XX G-M tube as a gamma radiation detector. The tube is
filled with a mixture of gases, one of which acts as a quenching agent, while the others tend to support
ionization. Electrically, it consists of a positive electrode (anode), which is maintained at a steady potential
of 500/650 Vdc and a negative electrode (cathode) that is near ground potential.

When a gamma photon penetrates the shield encasing the G-M tube, an ionizing event occurs. An ion
pair is produced, triggering an avalanche of ion pairs. The current pulses produced (one pulse per ionizing
event) are independent of the energy of the initiating particle. Multiple discharge, caused by the release of
electrons from the cathode due to excess energy, is eliminated after a short time (called dead time,
typically 20-45 microseconds) by a quenching gas within the tube. The resulting pulses are conditioned
and transmitted to the preamplifier.

The integral detector preamplifier provides input pulse discrimination and amplifies pulses received from
the G-M tube to 5 Vdc amplitude. The current drive output of the preamplifier will drive a signal up to 2000
feet through a 50-ohm transmission line, without signal degradation.

3-1

Should a very high intensity radioactive source be detected, the G-M tube may become saturated (i.e.
pulses are separated by a period less than the dead time of the tube). This would have the effect of
holding the preamplifier output at a relatively constant output voltage, resulting in count loss at the readout.
Anti-Jam circuitry in the preamplifier produces a full-scale output square wave signal, providing a full-scale
indication at the readout.

G-M Detector Response Time

The response time of the system to a step change in radiation value is 60 seconds, due to the operation of
the pulse counting algorithms. The detector radiation value displayed is the result of a rolling average of
the latest 60, one-second values, and is updated once per second. An alarm will be initiated within one
second after the current one-minute average exceeds the alarm setpoint.

Check Source

A manual check source may be initiated from the UDR by the operator to check detector operation. The
Check Source push-button is a momentary contact switch, and is active as long as the pushbutton is
depressed. Upon initiation and removal of the check source request, the internal counting registers are
cleared and the display value will be based on the number of new values received. After 60 seconds, the
display value will reflect the average of the past 60 values. During check source activation, analog outputs
are muted (forced to zero). The High and Warn alarms are normally inhibited during check source
operation, but may be enabled by removing Jumper JP3-5, on the UDR main printed circuit board (see
Table 2-12). The counters are cleared upon exiting Check Source mode, resulting in a display of 0.00.
After one minute, the current radiation value will be displayed.

3.3 UDR OPERATION, MODEL 956A-201-M2

Operation of the 956A-201-M2 UDR consists of operator functions and configuration functions. All
operator functions are performed using the front panel. Configuration functions are performed using
internal switches and/or jumpers that are accessible via partial removal of the UDR from the mounting
enclosure.

Normal Operation

If the measured radiation field is within the range of the detector during power-up, the mR/h value will be
displayed as a three digit number: N.NN, where N = 0 to 9. A backlit insert will display engineering units in
mR/h, R/h, or kR/h. The bargraph will display the value on the fixed mR/h scale and any indicator lights
that are on should be green, providing the operator with a visual indication of normal operation. The
analog outputs will track the displayed value, and the alarm outputs will be active. The Warn, High, and
Fail relays operate in the Fail Safe Mode.

WARN/HIGH Alarms

If the measured radiation field increases above the WARN alarm limit, the WARN alarm indicator will turn
on flashing (amber color), the bargraph will change color to amber, and the warn alarm relay will de­activate. If the measured radiation field increases above the HIGH alarm limit, the HIGH alarm indicator
will turn on flashing (red color), the bargraph will change color to red, and the high alarm relay will de­activate.

Non-fail-safe relay operation for the HIGH and WARN alarms is

available as a firmware option at time of purchase.

NOTE

3-2

The UDR can be configured to automatically reset the alarm relays and alarm indicators, or it can hold the
alarm relays de-energized and flash the alarm indicators until the alarm acknowledge (ALARM ACK)
pushbutton is pressed. If the ALARM ACK pushbutton is pressed while the alarm condition still exists, the
indicators will go to a steady state, and the relays will remain de-energized until the alarm condition returns
to normal. Upon resumption of normal operation, the relays will energize and alarm indicators will
extinguish. The bargraph color will always indicate the current status; green for normal, amber for warn,
and red for a high alarm.

Front panel pushbuttons labeled HIGH and WARN can be used to display the respective alarm set points.

To drive a local alarm, a 120 Vac is internally wired from alarm output connector P1 to the alarm relay
contact on P2-13 and 14. Refer to Modification Sheet 956A-201-M2MS and Loop Drawing S174014C-

102.

Range Alarm

If the measured radiation field is below the underrange setpoint (minimum range of the detector used), the
front panel display will indicate 0.00 mR/h, the bargraph will indicate the actual radiation value, and the
RANGE alarm indicator will illuminate in red. The minimum range is adjustable by the underrange
setpoint, and is defaulted to 1.00E-1 mR/h. When the measured radiation field increases into the range of
the detector, the RANGE alarm indicator will extinguish and normal operation will begin.

There are three ranges for the ratemeter, one for each detector range (low, medium, & high). The specific
range for each detector is established by operator-entered setpoints (refer to "Setpoint Entry" for actual
entry procedures). The detector range for each specific detector is shown below.

Detector

897A-210/211 0.01 to 10E3 mR/h 1.00E-2 1.00E3
897A-220/221 0.1 to 10E4 mR/h 1.00E-1 1.00E4
897A-230/231 1 to 10E5 mR/h 1.00E0 1.00E5

If the measured radiation field goes above the overrange setpoint, the RANGE alarm indicator will
illuminate and the front panel display will indicate EEEEE, the bargraph will illuminate in red, and the
analog output will be set to full scale. The maximum range of the detector used is determined by the
overrange setpoint. When the measured radiation field returns within the maximum operating range of the
detector and the condition is acknowledged, the RANGE alarm indicator will extinguish and normal
operation will resume.

In addition to the display of EEEEE when in Overrange, the

In the event the detector output exceeds the electronic anti-jam circuit trip level, the anti-jam fuse will open
and the Fail relay will change state to indicate a monitor not in service condition. Replacement of the anti­jam fuse (F1) will be required in order to return the rate meter to normal operation.

Detector Range

Underrange Setpoint Overrange Setpoint

NOTE

mR/h engineering units will be displayed if the HIGH or WARN

front panel set point display pushbuttons have been accessed.
IF desired, the mR/h units display may be cleared by either
pressing the ENTER push button, or cycling the UDR power
OFF/ON. The mR/h unit’s display, however, does not affect the
operation of the Overrange function.

FAIL Alarm

Detector failure, detector overrange, or microprocessor failure are some of the conditions which can
produce a FAIL alarm and in some cases an error display. The Fail condition is true whenever any
equipment failure is detected and false when no equipment failures are detected.

3-3

When a Fail condition occurs, other than power failure, the red FAIL alarm indicator illuminates and the
Fail relay coil de-energizes. On the 956A-201-M2, auxiliary relay K1 is hard wired to operate in parallel
with the Fail relay, to drive a local indicator. Internally, 120 Vac is hard wired from alarm output connector
P1 to the Fail relay contacts on P2-12, and 13. Refer to Modification Sheet 956A-201-M2MS and Loop
Drawing S174014C-102.

To return the channel to normal operation after a FAIL alarm, the condition that caused the alarm must be
located and corrected. Upon correction of the failure condition, the FAIL alarm will automatically close.

Check Source

The check source pushbutton and electronics are provided to verify detector operation. To operate the
check source, press the CHECK SOURCE pushbutton and hold it down. The Check Source LED will
illuminate, and the radiation value will increase. Releasing the check source pushbutton will allow normal
UDR operation. An internal configuration jumper (JP3-5) allows alarms to be activated or deactivated in
the check source mode. The analog outputs are forced to their low scale value during a check source
operation.

Trip Test, 956A-201-M2

A Trip Test Function has been added to the operating firmware of the 956A-201-M2. The purpose of the
function is to verify operation of the output relay, status indicators, display, and analog outputs.

Refer to the Operational Mode section for a complete description of Operation.

Firmware Version

This system requires a PROM for UDR operation. For the part number and the latest revision of the
PROM, see the Factory Test Data Sheet. Operation as described in this manual pertains to the PROM
defined in Section 1.1.

3.4 OPERATIONAL MODES

Normal Operation, Mode

The UDR is in normal operation when the UDR function switch is in any position except 8, and the Check
Source button is OFF. During normal operation, the display shows the dose rate data received from the
preamplifier in mR/h, R/h, or kR/h. The bargraph will also show the dose rate. The color of the illuminated
segments is green when the dose rate is below the WARN setpoint, amber when the dose rate is above
the WARN setpoint and below the HIGH setpoint, and red when the dose rate is above the HIGH setpoint.
The analog outputs are active and all alarms are enabled.

Data Entry Mode

Data Entry Mode is selected by pressing the ENTER pushbutton while the rotary FUNCTION switch is in a
valid setpoint position (see Setpoint Description). The selected setpoint is displayed in exponential
format (e.g. 1.00E2) with the left most digit flashing. Setpoints are entered in exponential format (e.g.
X.XXEN), where X is the mantissa and N is the exponent. The X value may be any integer value between
0 and 9. A positive exponent is entered by selecting the "E" symbol, and a negative exponent is entered
by selecting the "-" symbol. The N value may be any integer value between 0 and 9. If the FUNCTION
switch is not in a setpoint position, pressing the ENTER button has no effect. Refer to Table 3-3 for
FUNCTION switch positions.

In the Data Entry Mode, the bargraph and analog outputs remain active.

3-4