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Model 1786A Detector LN
Model 1786A
Detector LN
2
Monitor
Features
·
Protection against accidental detector warmup
·
Delayed shutdown saves experiments
·
Audible, visual and contact closure outputs
Description
The Model 1786A Detector LN
2
Monitor protects LN
2
cooled
detector systems against accidental warmup by monitoring liquid
level in the Dewar and providing audible and visual warning of
low liquid levels. It is suitable for most dipstick and integral type
cryostats, but is not suitable for portable cryostats.
The unit has provisions for turning off detector bias when an
alarm condition occurs to protect detectors and electronics from
damage. Shutdown does not occur until at least 20 minutes after
the condition is sensed, and well before total depletion of the liq-
uid nitrogen, so that ongoing experiments can continue without
interruption.
The 1786A must be manually reset following a power interrup-
tion. This will prevent HV Bias from coming on automatically
(and abruptly) when the power is restored.
Specifications
INPUTS
LN
2
DET. Rear panel BNC connector accepts input signal
from the LN
2
sensor.
OUTPUTS
H.V. CONTROL Rear panel contact closure output is
grounded during alarm conditions; open circuit during normal
conditions; provides signal for remote shutdown of Detector
Bias Supply which has an Inhibit input.
INDICATORS
H.V. OFF Front panel indicator lamp lights when the
controlled circuit and H.V. Control outputs are disabled.
BUZZER Internal buzzer gives audible warning of alarm
condition.
LIGHT Front panel LN
2
indicator light gives visual warning
of alarm condition.
CONTROLS
ACTIVATE-SETUP Front panel toggle switch disables
high voltage to allow alarm circuits to be set and checked with-
out damage to associated electronics.
LN
2
Front panel lighted pushbutton switch; pressing it clears
the alarm once alarm situation is corrected.
ACCESSORIES
LN
2
SENSOR KIT Includes a flexible sensor assembly, a
BNC connector, and instructions for installing the sensor in
standard Canberra cryostats. The kit will be installed by
Canberra if the 1786A is ordered with a detector, a cryostat
collar (CC-30), or a Dewar neck plug assembly.
CONNECTORS
LN
2
DET. and H.V. CONTROL Rear panel BNC, UG-
1094/U.
POWER REQUIREMENTS
+24 V dc 40 mA
+12 V dc 185 mA
24 V dc 0 mA
12 V dc 5 mA
PHYSICAL
SIZE Standard single-width module 3.43 x 22.12 cm (1.35 x
8.71 in.) per DOE/ER-0457T.
NET WEIGHT 1.2 kg (2.7 lb).
SHIPPING WEIGHT 1.9 kg (4.2 lb).
Benelux/Denmark (32) 2 481 85 30 Canada 905-660-5373 Central Europe +43 (0)2230 37000 France (33) 1 39 48 57 70 Germany (49) 6142 73820
Japan 81-3-5844-2681 Russia (7-095) 429-6577 United Kingdom (44) 1235 838333 United States (1) 203-238-2351
©2002 Canberra, Inc. All rights reserved.
Phone contact information
M0563 9/97 Printed in U.S.A.
For other international representative offices visit our Web Site:
http://www.canberra.com or contact the Canberra U.S.A. office.
System
Certified
I SO 9001