Ronan X90 Series - Manual (Page 5)

the tube output does not indicate a minimum
background value (due to a malfunction in the G-M
tube or its power supply) the process (and failure, if
used) relay automatically changes over, indicating
an alarm condition.
The failure alarm will occur anytime the output from
the tube is zero.
—————————————————————————
5.0 TIME DELAY OPTIONS
The basic time constant is 0.5 seconds to 40 seconds,
depending upon the span setting. Additional time delays
available are 0.1, 5, 10 and 20 seconds.
For most applications, the 0.1 second jumper is used. If
false alarms occur, the time delay should be increased.
The delay is selected by a plug-in jumper located on the
electronics chassis printed circuit board.
5.1 Relay Contacts
Two Form-C (SPDT) contacts are provided.
Contact ratings are 3 A at 30 Ddc or 120 Vac
resistive. Other forms of contacts may be provided
on request.
If both sets of contacts are to be used for the
process alarm relay, jumper A10, B-11 and C-12
(located on the X90-301(V) printed circuit board or
X90-1005 printed circuit board for the integral
version.) For the integral Model X90-1005, 10A
contacts are provided as standard equipment.
If one set of contacts is to be used for a failure
alarm relay, D10, E-11 and F12 are jumpered.
—————————————————————————
6.0 CIRCUIT DESCRIPTION
The X90-301(V) and X90-1005 circuitry consists of a
stabilized ± 12 V and 500 V power supply, a voltage
integrator, comparator and logic alarms.
The output pulses from the G-M tube are fed through an
emitter follower to the input circuit. The pulses are + 12
V, 200 microseconds wide.
The G-M tube output is integrated and amplified by the
input circuit. The zero and span controls are used to
generate a 0 to 1 V output for low to high level
conditions.
This output is monitored using a simple VTOM across
the test points, AMP and TP GRN. A comparator circuit
will trip the relay circuitry at 0.9 V and reset at 0.2 V.
Jumpers on the circuit board are provided to make the
switch function as a high-level or low-level limit alarm.
Complete circuit schematics and wiring diagrams are
provided at the end of this manual.
7.0 INSTALLATION AND ELECTRICAL
CONNECTION—GENERAL
All equipment manufactured by Ronan Engineering is
carefully packaged and shipped to prevent shipping
damage. Any discrepancies between shipping contents
and invoice should be immediately reported to Ronan or
the Ronan representative.
All Series X90 system components (source holder,
integral switch and remote tube assembly) will tolerate
normal industrial vibration. However, in cases where
vibrators are attached directly to the vessel, the system
components must be mounted on adjacent building
framework or use special supports that provide a degree
of isolation.
When the axis of the G-M tube is placed parallel to the
surface of the process material and its side-facing
source, relay contact changeover will be obtained when
the set limit is exceeded by about one-half inch. When a
coarser level limit is appropriate, a broad band of about
five inches can be obtained by placing the detector axis
perpendicular to the surface of the process material. In
either case, an alarm is produced after the tube is
obscured from (or exposed to) the radiation from the
source.
Whenever possible, separate power sources should be
used for the X90 and the alarm circuit. With this
arrangement, the alarm will operate if the power to the
X90 is interrupted (provided, of course, the alarm circuit
has power available).
Local electrical codes must be followed for all wiring. All
conduit entrances should be sealed to prevent
condensed moisture or water from entering the
enclosures. The cable used to connect the remote G-M
tube should also be run through conduit. All explosion-
proof housing covers must be replaced when the system
is in operation.
7.1 Remote Probe (X90-1004)
The G-M tube with X90-1004 driver board is placed
in an explosion-proof housing. This assembly is
mounted in position at the required level or point of
measurement and connected to the X90-301(V)
module by a four-conductor, shielded cable
supplied by Ronan Engineering.
Refer to drawing number C-1369-K for wiring of the
remote detector assembly and refer to drawing
number C-1359-K for designation of terminals on
the X90-301(V) module.
7.2 Model X90GPE
The X90-301(V) modules are plugged into X90GPE
surface-mount, single chassis enclosures. Access
to input/output and power connections are from the
front, beneath a convenient, snap-on cover.
Connections are located in a separate
compartment of the chassis and removal of the