Martel Electronics SP100 - Manual (Page 4)

Specifications liable to change without prior warning SP 100 Issue 3 October/2001 M.C. Applies to SP 100/1
APPLICATIONS
Do not connect more than one meter to the same power supply if the meters cannot use the same signal
ground. Taking any input beyond the power supply rails will damage the meter.
Page 4 of 4 Page 4 of 4
SCALING
Two resistors Ra and Rb
may be used to alter the
full scale reading (FSR) of
the meter - see table. The
meter will have to be re-
calibrated by adjusting the
calibration potentiometer
on the rear of the module.
FSR Ra Rb
2V 910k** 100k
20V 1M** 10k
Vin 200V 1M** 1k
2000V* 1M** 100R
200 A 0R 1k
2mA 0R 100R
in 20mA 0R 10R
200mA 0R 1R
µ
I
Voltage
Current
Page 4 of 4
* Ensure that Ra is rated for high voltage use.
** Ensure solder link LA is cut.
SP 100
3½ Digit LED Voltmeter Module
INH
INL
RI
RO
0V
0V
+
-
±200mV
V+
V+
DE
Measuring a single ended input
voltage referenced to supply, i.e. the
input voltage and the meter's power
supply share the same 0V rail.
INH
INL
COM
RI
RO
0V
0V
+
-
±200mV
V+
V+
DE
Measuring an input voltage referenced
to a floating supply, i.e. the input
voltage and the meter's power supply
are isolated from each other.
V+
V+
DE
5k
Set Zero
220k
R
INH
INL
COM
0V
0V
I +
I-
4-20mA
current loop RI
RO
Measuring a 4-20mA loop current.
The meter's power supply must be
isolated from the 4-20mA current
loop.
R= Reading at 20mA
160
RI
RO
COM
INH
+5V
Load
Shunt
R
L
V+
DE
V
A
S
1
INL
0V
Rs
7805
220nF 470nF
10uF
V
supply
Measuring supply voltage and current to a load.
Rs = 200mV
Display DP1, DP2 or DP3, by connecting to 0V, as required.
S selects between voltage and current measurement.
Ra and Rb shown scaled for 200V
1
FSR
(e.g. 0.1 / 400mW for 2A full scale) Ω
I
FSR
I
Ra=1M
Rb=1k
INH
INL
COM
RI
RO
0V
0V
R
V+
V+
DE
Measuring current.
The meter's supply is isolated
from the current being measured.
R = 0.2
I
FSR
+
-
Ra
Rb
INH
Vin or in I
INL
SP 100
LA
11
12
1
11
2
8
7
12
10
3
1
11
2
8
7
12
10
3
1
11
2
8
7
12
10
3
1
11
2
8
7
12
10
3
1
11
2
8
7
12
3
www.lascarelectronics.com
PO Box 770, Londonderry, NH 03053 1-800-821-0023
www.martelcorp.com