MHY 925
MHY 925
Input/output element with isolator
MHY 925 is an addressable multiple input/output element, containing 8 (4) programmable inputs and 8 (4) programmable outputs. It connects to a detection line of Fire Detection and Fire Alarm System LITES

MHY 925 is an addressable multiple input/output element, containing 8 (4) programmable inputs and 8 (4) programmable outputs. It connects to a detection line of Fire Detection and Fire Alarm System LITES, eventually on communication line SL-RS 485 of C.I.E. MHU 115. The element contains an isolator.

Inputs serve to automatic signalling of user defined states of any external device, which indicates this state either by closing or opening an electrical contact or by voltage received by the optoisolated input. Contacts can also be set as guarded.

Outputs serve to control of external devices connected to NO or NC relay contacts. MHY 925 is produced in two variants:
a) MHY 925/4 – contains 4 programmable inputs and outputs
b) MHY 925/8 – contains 8 programmable inputs and outputs

Properties of each input, conditions for activation and properties of each output are defined via the configuration program for C.I.E.s.

Electrical circuits are on a printed circuit board which is placed in a plastic box with removable cover. Connecting wires are connected to plug-in screw terminal blocks.

 

 

 

Operation principle

The element is powered by a pulse voltage from the detection line of C.I.E. It contains power supply for its own electronic circuits. Evaluation circuits of input can be set as optoisolated or for connection of switching or breaking contact. These inputs can be set as well as guarded, where with the external device an opening (FAULT) or closing (ALARM) contacts can be connected simultaneously. At the same time the loop is guarded for interruption or a short-circuit.

Addressable part registers the communication from C.I.E., reports under appropriate address and sends information about input activation to the C.I.E.

 

Technical parameters
Power supply (18 ÷ 21) Vimp
Stand-by current max. 200 μA
Number of outputs 4 or 8
Input optoisolated – voltage
input voltage 9 – 30 V (logical 1), 0 – 3V (logical 0)
input resistance cca 10 kΩ
Input NO/NC contact
resistance of wire and closed contact max. 1 kΩ
resistance of open contact min. 10 kΩ
output test voltage cca 12 Vimp
output test current (closed contact) max. 1,2 mA
Input guarded
test voltage 12 Vimp
line resistance max. 100 Ω
stand-by test current cca 0,8 mAimp
alarm test current cca 1,5 mAimp
fault test current cca 0,5 mAimp
stand-by resistance 10 kΩ
alarm resistance 4,7 kΩ
fault resistance 20 kΩ
Number of outputs 4 or 8
Maximal switching current 1 A
Maximal switching voltage 48 V
Maximal switching power 30 Wss> / 40 VAst
Usable for electricity grid no
Optical signalling red and yellow LED
Address adjustment (via MHY 535) 1 to 128
Protection according to ČSN 60529 IP 54
Radio screening degree according to ČSN 55022 B-class equipment
Cross-section of connectable wires (0,2 až 1,5) mm2
Dimensions (š × v × h) (254 × 180 × 63) mm
Weight cca 600 g