Dwyer MTL5045 User Manual
Page 25
21
INM5000-6 Jul 2010
6.17
MTL5040 2-channel 4 to 20mA loop
isolator
The MTL5040 provides a fully floating dc supply for energising a
conventional 2-wire 4 to 20mA transmitter located in a hazardous area.
It also passes on a 4 to 20 mA or 0 to 20mA signal from a controller
located in the safe area to a load in the hazardous area.
6.17.1 Wiring connections
See figure 6.35 for wiring connections.
6.17.2 Testing
Make the safe and hazardous-area connections shown in figure 6.36
and, using RV1 to vary the output current on channel 1, and using the
current source to vary the output current on channel 2, carry out the
checks shown in table 6.9
Table 6.9
6.18
MTL5041/42 repeater power
supplies
The MTL5041/42 provide fully-floating dc supplies for energising
conventional 2-wire 4 to 20mA transmitters located in a hazardous
area. They repeat the current in another floating circuit to drive safe-area
loads. The MTL5042 also provides similar facilities for 3-wire transmitters
and permits bi-directional transmission of 'smart' digital communication
signals superimposed on the 4 to 20mA signal.
Note: MTL5042 terminals 1 and 3 only support HART® communi-
cations in one direction from field device to safe-area connections 11
and 12.
6.18.1
Wiring connections
See figures 6.37 and 6.38 for wiring connections (MTL5041 and
MTL5042 respectively).
6.18.2 Testing
Make the safe- and hazardous-area connections shown in figure 6.39
and, using RV1 to vary the output current, carry out the checks shown in
table 6.10.
7
8
9
6
5
4
3
2
1
13
14
10
11
12
I
I
I
I
4/20mA
4/20mA
P
I
Vs
Vs+
20 to 35V dc
+
+
4/20mA
Figure 6.35: MTL5040 wiring diagram and connections
Terminal
Function
1
Input –ve (transmitter), ch 1
2
Input +ve (transmitter), ch 1
4
Output –ve (driver), ch 2
5
Output +ve (driver), ch 2
8
Input -ve (driver), ch 2
9
Input +ve (driver), ch 2
11
Output –ve (transmitter), ch 1
12
Output +ve (transmitter) ch 1
13
Supply –ve
14
Supply +ve
7
8
9
6
5
4
3
2
1
13
14
10
11
12
I
I
I
I
Vs
Vs+
20 to 35V dc
+
+
+
+
+
470W
Ch 2
Current
Source
Ch 1
RV1
10kW lin
A3
A1
A4
A2
Figure 6.36: Test circuit for MTL5040
Output current
Current reading
Channel 1 Voltage
(A2 for Ch 1 and
(A1 for Ch 1 and
(terminal 2 with
A4 for Ch 2)
A3 for Ch 2)
respect to terminal 1)
4 to 20mA
<±20
μA
20mA
>16.5V
Safe area
Hazardous area
6
5
4
3
2
1
7
8
9
10
11
12
13
14
Vs
Vs+
20 to 35V dc
+
4/20mA
HHC*
Load
+
4/20mA
HHC*
* Hand-held communicator
I
I
Figure 6.38: MTL5042 wiring diagram and connections
Hazardous area
Safe area
+
4/20mA
Vs
Vs+
20 to 35V dc
4/20mA
I
I
Load
+
6
5
4
3
2
1
7
8
9
10
11
12
13
14
Safe area
Hazardous area
Figure 6.37: MTL5041 wiring diagram and connections
6
5
4
3
2
1
7
8
9
10
11
12
13
14
I
I
Vs
Vs+
20 to 35V dc
10kW lin
RV1
A1
A2
+
+
Terminal
Function
1
Input –ve
2
Input +ve
11
Output –ve
12
Output +ve
13
Supply –ve
14
Supply +ve
Figure 6.39: Test circuit for MTL5041/2
Terminal
Function
1
Current Input
2
Transmitter supply +ve
3
Common
4
Optional HHC -ve
5
Optional HHC +ve
8
Optional HHC -ve
9
Optional HHC +ve
11
Output –ve
12
Output +ve
13
Supply –ve
14
Supply +ve