Fault Conditions - Thermo Scientific Prima PRO User Manual

Air Conditioner

Fault Conditions

Conditions
E-2 Prima PRO & Sentinel PRO Mass Spectrometers User Guide
4. Ambient air circulation over the condenser section is required
to allow dissipation of heat from the system. For safe area
systems, this is provided by a fan (24VDC). For ambient
temperatures below 28˚C, a series resistor (supplied) can be
used to reduce fan speed/noise.
5. For hazardous area systems, a bank of three air amplifiers is
used to provide a completely non-electrical, no moving parts
air circulation method. Air flow is determined by the air
regulator setting – up to 3 bar for ambient temperature up to
40˚C.
6. The 24VDC supply originates from the Power Distribution
Unit (PDU) within the instrument and, in addition to driving
the external fan, provides power for some of the internal
control logic for the air conditioner and provides an alarm
feedback to the PDU. To operate, the air conditioner requires
both mains power from the "Cooling" breaker in the main
enclosure and the 24VDC supply. The connection at the PDU
(3-pin) is as follows:
The following parameters should be monitored on a continuous basis
Fault
to help diagnose any suspected malfunction of the air conditioner, or
the reason for a malfunction. Additionally, simple functional
observations (external air flow and temperature, internal air flow,
valve 'clicking') can be useful. Measuring the mains current drawn
by the air conditioner (using a clamp meter around the live or neutral
supply wires) can give a useful indication of which parts are running.
Cabinet temperature - if the user is familiar with the normal pattern
of temperature cycling (frequency and span), or has this data
recorded, it is straightforward to see when a change has occurred.
Air conditioner 24VDC alarm – the frequency and duration of any
alarms should be monitored, as well as the actual voltage reading.
The 24VDC passes through three sets of series contacts before
returning to the PDU. Any one (or more) of these contacts being
open, or a fault in the 24VDC supply itself, could cause an alarm.
The three alarm contacts are:
a) Refrigerant low pressure
b) Refrigerant high pressure
c) Temperature controller alarm (temperature more than 2˚C
from set point)
Pin 1 (top) 24V (-)
Pin 2 (middle) 24V alarm return
Pin 3 (bottom) 24V (+)
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