The Recom Explorer 4 Multichannel Control Unit is an advanced gas monitoring device designed for continuous surveillance. It is a fixed-mounted instrument that can detect gas levels at up to four different locations simultaneously. The instrument’s display screens provide real-time gas readings for all active channels, allowing users to monitor multiple areas at once. Safety is a key feature of the Explorer 4, as it includes both audible and visual alarms to warn users of any hazardous gas conditions. The alarm circuit is equipped with three levels of gas alarms, ensuring that any potential risks are promptly identified. Additionally, the fail circuit is designed to alert users in case of gas transmitter or Explorer 4 failures, ensuring the reliability of the monitoring system.
To cater to various monitoring needs, the Explorer 4 can be connected to different types of sensor/transmitters that provide an analog signal in the range of 4-20 mA. This flexibility allows for compatibility with a wide range of gas sensors, enabling the detection of flammable gas mixes, toxic gases and vapors, oxygen levels, hydrocarbons (HC) or carbon dioxide (CO2), volatile organic compounds (VOC), and binary gases. Furthermore, the Explorer 4 is equipped with an RS232 serial port, enabling the transfer of data to a personal computer (PC). This feature facilitates data logging, analysis, and integration with other monitoring systems, enhancing the overall functionality and usability of the Explorer 4 gas monitoring instrument.
The sensors employed in the Explorer system utilize various measuring principles to ensure accurate gas detection. These principles include catalytic combustion for monitoring flammable gas mixes, electrochemical sensors for toxic gases and vapors, galvanic sensors for oxygen measurement, infrared sensors for hydrocarbon or CO2 monitoring, photoionization detectors (PID) for VOC monitoring (such as PCE, TCE, MEK, BTEX), and thermal conductivity (TC) sensors for measuring binary gases (like SF6 and H2).
The electrical signals generated by these sensors undergo amplification and linearization processes to obtain a standardized 4-20 mA signal. This analog signal is then transmitted through an electrical cable to the control unit, which is typically housed in a rack or central location.
The Explorer 4 can be installed in a ¼ 19″ rack suitable for installation in areas where general-purpose equipment is in use, such as a control room. All external wiring connections can be made on the back side of the device. It is important to avoid routing transmitter and power wiring through the same conduit hub to prevent electrical interference.
When connecting the electrical power supply, ensure that all connections to the Explorer 4 are made before plugging in or turning on the AC or DC power source. It is crucial to verify that all power sources are not live before making any wiring adjustments. The Explorer 4 is powered directly on terminals 2 and 4 using 24Vdc. The DC power can be supplied externally or through the power supply card located on the left side of the rack. The power supply card is designed to accept a universal AC voltage ranging from 100 to 250 Vac at 50/60Hz.
For the electrical connections of the sensor/transmitters, there are 4 terminal blocks available. These terminal blocks support both 3-wire loop current technology and 2-wire loop current technology. Each terminal block provides the following connections: +24Vdc (maximum 0.2A), input 4-20mA, output 4-20mA, and ground (0Volt).
In terms of external digital outputs (alarms), there are 3 programmable analog alarm thresholds for each enabled sensor. These thresholds trigger corresponding relays to indicate alarms based on specific conditions. The analog inputs of the Explorer 4 can be programmed channel by channel, allowing customization of various settings. This includes selecting the period over which the sensor readings are averaged (instantaneous, brief, long), setting the offset reading value, and choosing the measuring range (expressed in percentages or parts per million – PPM).
Housing | 4 – 8 – 16 channel rack and wall cabinet |
Dimensions | (4 pos. rack): width 105 mm (21U), height 132.5 mm (3HE) |
Weight | 1.7 kg approx. |
Data display | LCD display, 2x20 characters |
Measuring range | %, ppm, other programmable quantities |
Power supply | 24Vdc nominal / 100-250 Vac with power supply |
Power consumption | 5 W on no-load, 25 W with all the alarms active |
Number of channels | from 1 to 4, SW enabled |
Alarms | Alarms 3 thresholds, programmable from 0 to 100% f.s. |
Analog signal inputs | 1 per channel, 4-20 mA |
Audible indicators | 1 buzzer activated in the event of an alarm |
Visible indicators | 4 LEDs per channel / 1 fault + 3 alarm thresholds + 1 status ON indicator LED |
Relays | 3 NO outputs per channel (1 for each threshold), 1 general alarm relay and 1 fault relay common to the 4 channels |
Buttons | 3 multifunction buttons |
Analog output | 4-20 mA for each channel |
Sensor power supply | 24 V dc |
Operating temperature range | from –20° to +55° C |
Moisture | from 0% to 95% Rel. humidity without condensation |
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