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Explosion proof | Applications Schischek GmbH Explosionproof
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Explosionproof

 

Correct installation
For the installation of electrical systems in areas with explosive gas atmospheres of group II, rule IEC 60 079-14 (EN 60079-14) will apply.

Electric circuits of protection types d, e, q, o, m, p
Installation in the panel is identical to ”standard” installation, however the pro-
cedures for connecting Ex equipment must be followed. This refers, for example to voltage, current, fuses and motor protection equipment, etc. The require-
ments for specific products must be taken from their corresponding test certifi-
cates, standards and prescriptions as well as from the guidebook. It is only permitted to work on electric circuits within the Ex-area (for example when connecting to Ex-e terminal box if the voltage has been switched off). An Ex-e terminal box should only be opened after the voltage has been switched off.

Electric circuits of protection type „i“ (intrinsically safe)
For the planning and operation of switchgears and control systems installed in the safe area, but which contain circuits leading into the Ex-area, certain requirements should be considered. This applies especially to intrinsically safe circuits. Intrinsically safe circuits and non-intrinsically safe circuits should be kept separate. Minimum distances (distances) between bare connections must be observed, the cables must not produce any inadmissible external induc-
tance or capacitance. The maximum admissible electrical limits of Ex-i equip-
ment must be observed at all times. Intrinsically safe and non-intrinsically
safe electrical circuits should not cross, however it is allowed between two in-
trinsically safe circuits. Intrinsically safe circuits must be clearly marked.

Intrinsically safe circuits are marked by a „light blue“ color. This color is re-
commended for all intrinsically safe circuits to prevent confusion and/or linking up to a non-intrinsically safe circuit. Examples: cabels, cables, cable conduits, dampers, connection boxes, cable connectors,...

A minimum distance of 50 mm should be allowed between intrinsically safe and non-intrinsically safe circuits, and a minimum distance of 6 mm between two different intrinsically safe circuits. During installation the cables of intrinsically safe and non-intrinsically safe circuits should be laid out separately!

Suggestion on how to create a pannel
It is necessary to keep intrinsically safe and non-intrinsically safe equipment separate. It is recommended, in this case, that a sufficient distance be kept, to avoid extra costs in the future.

Large transformers, frequency rectifiers, large relays and other electric equip-
ment that may influence intrinsically safe circuits by inductance or capacitance should be installed at a sufficient distance. As a precaution Ex-i equipment should have a suitable cover to protect it from incorrect handling. The appro-
priate standards and regulations must be observed.


Schischek actuators and sensors in a typical air-handling system
Schischek actuators and sensors in a typical air-handling system

Applications in control systems

Air safety dampers - Air control dampers - Fire/smoke dampers

Air damper control

Air damper control

Schischek actuators are approved for direct installation and operation in explosion risk areas, as they are of the highest explosion groups and temperature class and are suitable for all gases, vapors, steam and dust. The electrical connection is made via an explosion proof terminal box (type ExBox-...). Please ensure during installation that all cables are securely fixed and connected in such a way that they are protected from mechanical damage.


Automatic air damper control

Automatic air damper control

In this example the control system consists of an actuator and a ExCos-D transducer with ExPro probe. The combination can be installed directly into the Ex area. The transducer converts the probe signal into an active signal (0...10 VDC or 4...20 mA) for input in a PLC systems. The output signal from the controller goes directly to the actuator. Between sensor and control-
ler is no additionally Ex i module and also no intrinsically safe (IS) wiring methode required. For the actuator and transducer the maximum permissible surface tempe-
ratures have to be taken into account.


Control of fire and smoke dampers

Control of fire and smoke dampers

In applications for fire/smoke dampers, the actuator has to reliably return the damper to its safety position via an external switch/contact. The actuator will return the damper to its safety position by an internal spring. The contact comes from a safety thermal trigger type ExPro-TT-.. which is directly connected to the actuator.



Heating - Cooling - Humidification - VAV control

Heating - Cooling control

Heating/Cooling control

In this example the control system consists of an actuator and a ExCos-D transducer with ExPro probe. The combination can be installed directly into the Ex area. The transducer converts the probe signal into an active signal (0...10 VDC or 4...20 mA) for input in a PLC systems. The output signal from the controller goes directly to the actuator. Between sensor and control-
ler is no additionally Ex i module and also no intrinsically safe (IS) wiring methode required. For the actuator and transducer the maximum permissible surface tempe-
ratures have to be taken into account.


Humidity control

Humidity control

In this example the control system consists of a valve actuator and an ExCos-D trans-
ducer with ExPro probe. The combination can be installed directly into the Ex area. The transducer converts the probe signal into an active signal (0...10 VDC or 4...20 mA) for input in a PLC systems. The output signal from the controller goes directly to the actuator. Between sensor and control-
ler is no additionally Ex i module and also no intrinsically safe (IS) wiring methode required. For the actuator and transducer the maximum permissible surface tempe-
ratures have to be taken into account.


VAV and differencial pressure control

VAV and differencial pressure control

In this example the control system consists of an actuator and a differential pressure ExCos-P transducer. The combination can be installed directly into the Ex area. The transducer converts the differential pres-
sure signal into an active signal (0...10 VDC or 4...20 mA) for input in a PLC sys-
tems. The output signal from the controller goes directly to the actuator. Between sensor and controller is no additionally Ex i module and also no intrinsically safe (IS) wiring methode required. The controller, situated in the safe area will, depending on changing circumstances being monitored, control a fan (must be Ex proof) or a mo-
dulating damper actuator (also Ex proof) to maintain the required air volume/pressure.



Thermostats - Humidistats - Pressurestats - Filter protection

Thermostat (binary sensor for temperature °C)

Thermostat (binary sensor for temperature °C) for use in explosion proof areas

ExBin-D… modules with ExPro-BT… is a sensor probe with a thermostat for use in explosion proof areas. No intrinsic safe electrical circuit and no transducer in the electrical control-panel are necessary. The module should be installed directly into Ex area, depending on demand in zone 1, 2, 21 or 22. The output contact can be used for sequence functions (relays, contacts, direct circuit, ...).


Hygrostat (binary sensor for humidity %rH)

Hygrostat (binary humidity sensor) for use in Ex-area

ExBin-D… modules with ExPro-BF… is a sensor probe with a hygrostat for use in explosion proof areas. No intrinsic safe electrical circuit and no transducer in the electrical control-panel are necessary. The module should be installed directly into Ex area, depending on demand in zone 1, 2, 21 or 22. The output contact can be used for sequence functions (relays, contacts, direct circuit, ...).


Filter monitoring with differential pressure switch

Filter monitoring with differential pressure switch

ExBin-P… modules are pressostats like Ex-differential pressure switches, e.g. for filter monitoring in explosion proof areas. No intrinsic safe electrical circuit and, no transducer in the electrical control-panel are necessary. The module should be installed directly into Ex area, depending on demand in zone 1, 2, 21 or 22. The output contact can be used for sequence functions (relays, contacts, direct circuit, ...).



Fan belt monitoring - Frost protection

Fan belt monitoring with differential pressure sensor/air paddle

Fan belt monitoring with differential pressure sensor/air paddle

ExBin-P… modules are pressostats like Ex-differential pressure switches, e.g. for fan belt monitoring in explosion proof areas. No intrinsic safe electrical circuit and, no transducer in the electrical control-panel are necessary. The module should be installed directly into Ex area, depending on demand in zone 1, 2, 21 or 22. To indicate fan failure switching modules are delivered with integrated time running relay with delay on start up. The output contact can be used for sequence functions (relays, contacts, direct circuit, ...).


Fan belt monitoring with inductive sensor (Namur sensor)

Fan belt monitoring with inductive sensor (Namur)

ExBin-N… modules with connected Namur sensor (inductive proximity switch) are especially for contact-free fan belt monitoring of ventilators, for use in explosion proof areas. No intrinsic safe electrical circuit and, no transducer in the electrical control-panel are necessary. The module should be installed directly into Ex area, depending on demand in zone 1, 2, 21 or 22. To indicate fan failure switching modules are delivered with integrated time running relay with delay on start up. The output contact can be used for sequence functions (relays, contacts, direct circuit, ...).


Frost protection monitoring over binary sensor with capillary

Frost protection monitoring with binary sensor in Ex area

ExBin-FR… are sensors are for frost protection monitoring with a capillary as measuring element for use in explosion proof areas. No intrinsic safe electrical circuit are, no transducer in the electrical control-panel are necessary. The module should be installed directly into Ex area, depending on demand in zone 1, 2, 21 or 22. The output contact can be used for sequence functions (relays, contacts, direct circuit, ...).

platz
     

Products for
zone 1, 2, 21, 22
(Example ExMax)

Products for
zone 2, 22
(Example RedMax)

Products for
safe area
(Example InMax)

 
 
 
 
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