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BETA Monitoring
Monitoring of Electrical Values
7
LQ3 insulation monitors for medical premises
13/25
Siemens ET B1 · 10/2008
13
*
You can order this quantity or a multiple thereof.
■
Overview
Medical premises require additional protective measures
against the occurrence of excessively high touch voltages.
In rooms that conform to Group 2 of DIN VDE 0100-710, any
interruption to the examination and /or treatment of patients
would place those patients at risk.
This is prevented through the use of changeover and monitoring
units. These monitor the insulation resistance of the non-grounded
IT system, the load current and the temperature of the transformer.
A warning signal is output if the limit values are exceeded. This
function is carried out by an insulation monitor.
In addition, a special voltage relay monitors the voltage of the
power supply and switches to a second power supply if it falls
below the specified limit values.
■
Benefits
•
Systems engineers can tailor the changeover and monitoring
unit at the control cabinet to suit individual requirements.
•
Binary inputs and actuators support connection of the
changeover and monitoring unit to any bus system. This
permits integration in existing systems.
•
Easy operation over potentiometers, the set limit values are
always visible.
■
Technical specifications
Insulation monitors
7
LQ3 354
7
LQ3 355
Standards
EN 61557-8
Power supply U
v
V AC
230
Operating range
× U
v
0.9 … 1.1
Supply frequency f
v
Hz
50 … 60
Power loss max. P
v
VA
Approx. 7
Rated system voltage U
n
(
measuring circuit)
V AC
0 … 300
Rated frequency f
n
Hz
10 … 1000
EMC immunity to interference
IEC 61000-6-2
EMC emitted interference
IEC 61000-6-3
Insulation coordination
IEC 60664-1
Rated impulse withstand voltage
kV
4
Degree of pollution
3
Flammability class
UL 94V-0
Measuring circuit insulation monitoring
Response value R
resp
k
50
50 ... 500
Response deviation
DIN VDE 61557-8
Response time t
on
at R
on
= 50 k , C
e
= 1 μF
R
F
from
to 0.5 × R
on
s
< 1.3
R
F
from
to 0 k
s
< 0.7
Hysteresis
%
15
Measurement voltage U
m
V DC
Approx. 15
Measurement current
I
m
max (at R
F
= 0 )
μA
< 50
Internal resistance DC R
i
k
> 250
Impedance Z
i
at 50 Hz
k
> 250
Permissible direct interference voltage U
fg
V DC
< 300
Measuring circuit load current monitoring
Response value, adjustable
with external transformer 50/5 A, Class 1
A
5 … 50
Hysteresis
%
4
Temperature influence
%/
°C
0.05
Time delay t
v
,
adjustable
s
0.1 … 20
Measuring circuit temperature monitoring
Response value
k
3.2 … 3.8
Release value
k
1.5 … 1.8
PTC thermistor
Acc. to DIN 44081/44082 Unit(s)
1 … 6
in series
Display and control elements
Operating error
Acc. to IEC 61557-8
LED display
•
Current and temperature monitoring
•
Ready-to-run
•
Insulation fault
•
Line breakage monitoring of the isolation measuring circuit
One red and one green LED
Green
Red
Red
•
Display of current insulation resistance
--
11-
step LED chain
Pushbuttons
Test and Reset
© Siemens AG 2008