Operating instructions

INTRODUCTION
20 Sep 12 1-5
DE-7200VFDCentrifuge
the upper setpoint, the compressor and condenser motors are cycled on to provide cooling. Upon
reaching the low temperature setting, the air conditioner is shut down. The evaporator fan
operates continuously whenever the cabinet is energized to maintain a continuous flow of
conditioned air over cabinet components.
Purge System (Hazardous Environment Only)
For operation in a hazardous environment, the control cabinet is equipped with a purge system.
The purge system ensures that the cabinet interior remains free of potentially hazardous gases by
filling the cabinet with filtered air and maintaining positive pressure to exclude ambient gases.
During startup, before power is permitted to enter the cabinet, the cabinet purge system initiates a
16-minute rapid purge cycle at 16CFM. When the rapid purge cycle is completed, the purge
system automatically closes a switch that supplies power to the cabinet.
Following the rapid purge, the purge system maintains a positive pressure inside the cabinet to
exclude any potentially hazardous gases. Minimum pressure and purge flow sensors will shut
down power if the purge system is not maintaining satisfactory pressure in the cabinet. For further
details of purge system operation, refer to Section 4.
Vibration Switch
The vibration switch (Figure 1-4) is a safety device designed to protect personnel and equipment
by shutting down the centrifuge in case of excessive vibration. Normally, the switch contacts are
held closed by a magnetic latch. However, strong vibration or a shock of 2 Gs will overcome the
magnetic latch, causing the switch armature to break away from the normally closed position,
providing an input to the PLC. A reset button on the side of the switch must then be manually
pressed to close the contacts and re-engage the magnetic latch.
WARNING!
EXCEEDING THE 2 G SETTING CAN CAUSE INJURY TO
PERSONNEL OR DAMAGE TO EQUIPMENT.
DO NOT RAISE THE SETTING.
The vibration switch is mounted on the centrifuge base in an orientation that is most affected by
out-of-balance vibration of the bowl assembly. Clogging of the conveyor or worn bearings may
produce sufficiently high vibration to trip the switch.
Figure 1-4 Vibration Switch
Case and Base
When the top cover is closed, the case provides a sealed, protective enclosure that fully
surrounds the bowl assembly. The liquid discharge chute and solid discharge chute are installed
at the bottom of the lower case half. Mating baffles installed inside the top and bottom case halves
separate the solid and liquid phases. Bolts secure the top and bottom halves together; a gasket in
the bottom case half seals the two halves.