1.12.3 Safety sensors
The iH system has a number of safety sensors, which are connected to the relay interlock
circuit. If any of the safety sensors cause the interlock relay to operate, the iH system is
immediately shut down.
The iH system can also be fitted with a photohelic switch accessory. If it operates, all electrical
power to the iH system is removed via the disconnect box. (See Section 1.18 and 1.19)
Table 1-1 shows the safety sensors and the shut down conditions.
Safety sensor Shut-down condition
HCDP pump-motor thermistor When the thermistor in the HCDP pump-
motor indicates that the temperature of the
pump-motor is nominally 150
o
C.
HCMB pump-motor thermistor * When the thermistor in the HCMB pump-
motor indicates that the temperature of the
pump-motor is nominally 150
o
C.
HCDP pump shut-down thermistor
When the thermistor indicates that the
temperature of the HCDP pump-headplate
manifold is 60
o
C or higher.
Exhaust pressure transducer
When the pressure in the exhaust pipeline is 9
psig or higher.
Photohelic switch
#
When the pressure in the enclosure exceeds
the setpoint.
* iH600/iH1000 only.
#
Accessory
Table 1-1 - Safety sensors
1.13 Pump display terminal
The Pump Display Terminal allows you to manually control the iH system and to display the
status of the iH system. Refer to Figure 1-8 which shows the front panel of the Pump Display
Terminal.
Use the On button (1) to switch on the iH system (refer to Section 5.6). The On button has a
green LED which is illuminated when the iH system is on. Use the Off button (10) to switch
off the iH system (refer to Section 5.10).
The display (2) shows two lines of text; each line is 16 characters long. In normal operation,
the Normal display is shown; the Normal display has two pages, and each page has two lines.
Each page of the Normal display shows the current status of one or more iH system sensors
or internal clocks and counters.
1-22 iH Dry Pumping Systems
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