Specifications liable to change without prior warning EMV 1025S-X X Issue 4 August/2002 M.C. Applies to EMV 1025S/1
TERMINAL FUNCTIONS
SAFETY
1. Red V+ Positive powersupply connection.
2. Black GND Negative power supplyconnection.
3. Yellow IN HI Positive measuring input with referenceto GND.
To comply with the Low Voltage Directive (LVD 93/68/EEC), input voltages to the module’s pins must not exceed 60Vdc. The user must
ensure that the incorporation of the unit into the user’s equipment conforms to the relevant sections of BS EN 61010 (Safety
Requirements forElectrical Equipment for Measuring,Control and Laboratory Use).
VOLTAGE SCALING
Two resistors Ra and Rb may be added in order
to alter the full scale reading (FSR) of the meter -
see table and diagrams below. The meter may
be re-calibrated by adjusting the calibration
potentiometer at the rear of the module.
CURRENT SCALING
A current shunt Rs may be added in order to
alter the full scale reading (FSR) of the meter -
see table and diagrams below. The meter may
be re-calibrated by adjusting the calibration
potentiometer at the rear of the module.
The module shown is an EMV 1025S -0 2
S selects between voltage and current measurement
Voltage: Ra, Rb and Rcal scale the module for 20V
1
FSR
Current: Rs = 200mV
(e.g. 10m / 4W for =20A)
Calibration:
First calibrate the current range, by adjusting the meter's own calibration
potentiometer. Then calibrate the voltage range, by adjusting the R
potentiometer.
Ω I
FSR
I
FSR
CAL
IN HI
Load
Shunt
R
L
V
A
S
1
Rs
V
supply
(8-30V)*
V
supply
(8-30V)*
I
Ra=1M
Rb=8k
+5V
V+
GND
7805
220nF 470nF
IN HI
+5V
Load
V+
GND
Rs
Measuring current.
Rs = V
FSR
FSR
I
7805
220nF 470nF
I
Do not connect more than one meter to the same power supply if the meters cannot use the same signal ground. Do not connect IN HI to a voltage greater than
(V+ - 1V )or to a voltage lower than (-(V+) + 1V) if the meter is unscaled, as this may damage the meter. Keep leads short to ensure noise-free operation. To
maximise measurement accuracy, use high precision (1%), low temperature drift (50ppm/°C or better) scaling resistors (Ra, Rb and Rs).
APPLICATIONS
Measuring a single ended input
referenced to supply.
V+
GND
0V
Vin
Ra
Rb
Voltage to be
measured
IN HI
0V
V+
+3.5 to +7.5V d.c.
Supply Voltage
Measuring supply voltage and current.
R
CAL
=5k
Required I Rs P
FSR
(Power Rating)
200uA 1k 0.04mWΩ
Ω
Ω
Ω∗∗
Ω∗∗
Ω
2mA 100 0.4mW
20mA 10 4mW
200mA 1 40mW
2A 100m 400mW
20A 10m 4W
200A 1m 40W
Ω
Required V Ra Rb
FSR
2V* 910k 100k
20V* 1M 10k
200V* 1M 1k
ΩΩ
ΩΩ
ΩΩ
* Consult 7805 voltage regulator manufacturer's datasheet for minimum and maximum allowable input voltage ratings.
* Subject to a minimum order quantity of 50
pcs., pre-scaled modules are available from
Lascar. See stock number table on the front of
this datasheet. Customer-specific scaling options
may also be available on request. Contact Lascar
sales office for details.
** We recommend that purpose made shunts
are used for these ranges.
PO Box 770, Londonderry, NH 03053 1-800-821-0023
www.martelcorp.com
QM150V-02
Martel.
Martel
(2 pages)
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