Section III. TECHNICAL PRINCIPLES OF OPERATION
Functional Description of Laboratory Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Functional Description of Laboratory Unique Equipment. . . . . . . . . . . . . . . . . . . . . . . . .
1-13. FUNCTIONAL DESCRIPTION OF LABORATORY SYSTEMS.
The following paragraphs describe the systems within the design of the Airmobile Laboratory. For
details of major equipment refer to the appropriate technical manual.
Electrical System (Refer to Figure 1-4). The Airmobile Laboratory has an input power
requirement of 208V, 3-phase power. Power is supplied by an external generator through a 50-
foot (15-meter), 8-wire cable (W1). Power enters the laboratory via connector receptacle J1.
From J1 power is applied to CB1 in the panelboard assembly. CB1 is a 100-amp, main power
input circuit breaker which incorporates an undervoltage trip feature.
Panelboard Assembly. The panelboard assembly houses all equipment circuit
breakers. There are fourteen 15-amp circuit breakers, (for equipment and convenience
outlets), and two 20-amp circuit breakers (for the environmental control units). The
following items are also contained in the panelboard assembly.
Fuse F2. Fuse F2 is a 15-amp fuse used to protect the components which
make up the control devices used during purging operations.
Purge System Power Relay (K2). This relay is used to turn on the control
devices for the purge system. It routes A-phase power via F2. The operating state
of the relay is not energized. When energized, control voltage used to operate
components of the purge system is removed.
Time Delay Relay (K3). The relay, along with the 6 Mohm resistor,
provides a 5-minute delay before applying power to relay K2. The 5-minute delay
is for the 5-minute purging cycle that is automatically started when power is
supplied to the laboratory after a shutdown. Power to the relay is routed from A-
phase input, through 5-amp fuse F1, and through the gas detector and alarm
system. During normal operation the time delay relay keeps relay K2 energized.
In the event of toxic gases being detected by the gas detector and alarm system,
power would be removed from the time delay relay which would deenergize relay
K2. This would then begin a purge cycle that would last 5 minutes after the gas
detector and alarm system has reset itself and power reapplied to the time delay
Fuse F1. Fuse F1 is a 5-amp fuse which is in-line with the time delay relay
as a protection device.