4
4.1.4. The Cooling State
In the cooling state, the AC POWER and BIAS OFF
LEDs are lit while the MAINS FAIL, HOLDING, and
WARMING LEDs are off. The compressor power is
reapplied, but the detector bias supply is held off.
The system will remain in the cooling state for the
period set on the internal BIAS OFF TIME switch, after
which the BIAS OFF LED will go out and the detector
bias voltage can be reapplied. The system will then
return to normal operation (see Section 4.1.1).
The cooling period (bias-off time) is set to a value long
enough for the detector to be cooled to a temperature
where it is safe to re-apply the bias voltage.
If the mains supply fails during the cooling period, the
CryoSecure will return to the start of the warming state.
4.2. SETTING THE HOLDING TIME
The holding time, which is the time the CryoSecure
waits after a mains failure before going into the warming
state, is set with the two rotary selector switches
mounted along the top edge of the controller PWB,
labeled HOLD HI and HOLD LO.
DANGER
Isolate the controller from the mains
power supply before removing the
cover.
The switches are BCD-type selectors, each with
settings from 0 to 9. The number set on the switches
corresponds to the holding time, with each unit of the
number set representing 5 minutes. The following table
give examples of some possible settings.
HOLD HI
HOLD LO
Time
(min)
Time
(h:min)
0
1
5
0:05
1
0
50
0:50
3
5
175
2:55
9
9
495
8:15
4.3. SETTING THE WARMING TIME
The warming time, which is the time the CryoSecure
waits after a mains power failure before restarting the
compressor, is set with the two rotary selector switches
mounted along the top edge of the controller PWB,
labeled WARM HI and WARM LO.
The switches are BCD-type selectors, each with
settings from 0 to 9. The number set on the switches
corresponds to the warming time, with each unit of the
number set representing 1 hour. The following table
gives examples of some possible settings:
WARM HI
WARM LO
Time (h)
0
1
1
1
0
10
3
5
35
9
9
99
4.4. SETTING THE COOLING
(BIAS-OFF) TIME
The cooling, or bias-off, time is the time the CryoSecure
waits after restarting the compressor before allowing the
detector bias voltage to be reapplied. It is set with the
rotary selector switch mounted along the top edge of the
controller PWB, labeled BIAS OFF.
The switch is a hexadecimal-type selector with settings
from 0 to F. The number set on the switches
corresponds to the holding time, with each unit of the
number set representing 2 hours. The following table
give a list of the possible settings:
Switch Setting Time (h) Switch Setting
Time (h)
0
0
8
16
1
2
9
18
2
4
A
20
3
6
B
22
4
8
C
24
5
10
D
26
6
12
E
28
7
14
F
30
4.5. DEEP DISCHARGE PROTECTION
In the event of a long-term power failure or if the mains
is switched off for a long period, the battery, normally
charged to 6.75 V, will eventually discharge to 5.25 V.
When this voltage is reached, a self-holding relay will
de-energize, disconnecting the battery. The CryoSecure
will then be in the shipping/storage-preparation state
described in Section 5.2. The battery will reconnect
automatically when mains power is restored, and the
system will go into the “safe” state described in
Section 3.2.
