The overtemperature circuit compares the air temperature to a reference level, generates an interrupt, and
turns off the heat if the air temperature is higher than the reference level. The overtemperature circuit requires
varying its voltage levels to accommodate various thermistor measurements. This is because the calibration is
digital (no potentiometer).
The watchdog circuitry monitors the 80C188 microprocessor, and monitors the +5V and +5VSTBY voltages.
It generates the interrupt signal and power failure signal to the 80C188 microprocessors. The audio circuit
includes a 8752 microcontroller that reads a wavetable located in a PROM and sends the table to a digital
audio circuit and amplifier. The high priority (HP) and other alarm signal lines select an output at the correct
frequencies.
Three OR gates are combined to generate the error signal. The inputs to the circuit are overtemperature, power
failure, and system failure. This circuit generates an error signal that turns off the heater and sounds the HP
alarm. This circuit is independent of the microcontroller.
1.2 Relay Board
The Relay Board includes 2 safety relays, which close to supply mains power to the heater and motor circuits.
Safety relay 1 is wired in series with the primary coil of the isolation transformer for the incubator and radiant
warmer heaters. Safety relay 2 closes the mains supply to the humidifier isolation transformer and the
transformer for the e-base and canopy motors. Control signals for the two relays originate on the Control
Board.
The Relay Board interfaces the DC control signals to the two chassis mounted solid-state relays (SSRs), which
control the incubator and radiant warmer heaters individually. The control signals for the two heater SSRs
originate on the Control Board.
The Relay Board includes a SSR for the humidifier. The SSR output is wired in series with the humidifier heater.
The humidifier SSR control signal originates on the Control Board.
There is one current sense circuit for the incubator and radiant warmer heaters and an additional one for the
humidifier heater. These circuits consist of a small signal transformer that produces a current proportional to
the current through the heater circuits. The current is rectified and measured. The subsequent comparator
then generates a digital level based on a specified current level. This results in a signal to the Control Board
representing the state of the heater (on or off).
The two line compensation circuits consist of a signal transformer connected to the mains voltage. The
secondary of this transformer feeds a full wave rectifier and capacitor. The resulting DC voltage is proportional
to mains voltage, and it is measured on the Control Board.
The line frequency circuit consists of a full wave rectifier and a comparator. This circuit generates a digital pulse
with frequency twice that of the line frequency (50 or 60 Hz). The output signal is provided to the Control Board.
The Relay Board provides the +5v standby power supply to the entire Giraffe system. A +5V regulator generates
the +5V standby from the diode OR combination of the 12V power supply or the backup battery. If
there is no mains power, then +12v is not present, and the battery will generate the +5V standby. When +12V
© 2001 by Datex-Ohmeda, Inc.. All rights reserved.
6600-0343-000 104
3
Chapter 1: Functional Description
Содержание Giraffe OmniBed
Страница 10: ...x 6600 0343 000 104 2001 by Datex Ohmeda Inc All rights reserved Table of Contents ...
Страница 28: ...xxviii 6600 0343 000 104 2001 by Datex Ohmeda Inc All rights reserved About this Manual ...
Страница 38: ...10 6600 0343 000 104 2001 by Datex Ohmeda Inc All rights reserved Chapter 1 Functional Description ...
Страница 48: ...20 6600 0343 000 104 2001 by Datex Ohmeda Inc All rights reserved Chapter 2 Service Checkout ...
Страница 56: ...28 6600 0343 000 104 2001 by Datex Ohmeda Inc All rights reserved Chapter 3 Calibration and Maintenance ...
Страница 260: ...232 6600 0343 000 104 2001 by Datex Ohmeda Inc All rights reserved Chapter 6 Illustrated Parts ...