INST-10121514
Section 1. Description
Simco Worksurface Tester Model ST 4 is a portable, easy-to-use instrument for use in-
evaluating a wide variety of ESD protective materials including table mats, floor mats, hard
laminates, conductive floors etc.
Simply ST 4 will start measure by leave on the object you attempt to measure. S T 4 also has--
timer inside to avoid remaining/leaving ON condition although not used.
Additionally resistance to ground function of the same range is provided to permit resistance
measurements to be made from any points on the surface being tested to ground to indicate
total system resistance of the mat, ground lead and connection.
ST-4 accurately measures and displays surface resistivity in the range from
10 10 Ω square.
3
〜／
１３
Section 2. Principle of measurement
Worksurface Tester Model ST 4 has a built-in voltage source that places a potential difference-
(V) of 10V or 100V DC between the parallel conductive probes. The source can deliver up to
10mA or 1mA of current, and it is measurement of t his current (I) that is used to determine
the surface resistivity. The resistance between the probes (R) is calculated automatically in the
tester using Ohm's Law
R=V/I
ST 4 has one-chip micro-processor and it can provide very precise measurement and-
wide-rage registancy. See below the diagram of ST 4.-
Low resistansy rubber covered probe (10 Ω/ or below) is attached on the surface to be-㎝
２
tested and the standard voltage (10V or 100V ) is charged to the surface to be tested thru
protective resistance inside.
The arrangement of the probes makes the resistance measurement in ohms equivalent to the
surface resistivity in ohms per squre. ST 4 tester displays the resistivity, after logarithmic-
conversion, as an exponent of LCD. a block diagram of the circuit is shown in fig.1
fig.1 Diagram of the circuit
−−page 4
INST-10121514
Section 3. Specification
１０ 〜１０ （ Ω）Surface Resistivity : Ω/sq. or
３１３
Mode : Standard Mode(Ohm per square, Surface Resistivity)①
Mat surface - Mat resistance measurement Mode (Ohms, Resistivity to Ground)②
(w/ cable)
IEC Standard measurement Mode③
follow the IEC standard probe (surface + weight)
LCD display : Exponent display (one digit beyond the decimal point)
Remaining measurement time by bar-graph indicator
Remaining battery value
LED display : TEST①
Green LED indicator: Standard Mode(Ohm per square, Surface Resistivity)
Red LED indicator: Mat Ground resistance measurement Mode-
(Ohms, Resistivity to Ground) and IEC standard measurement Mode
Measurement voltage (10V,100V)②
Green LED indicator: 10V output
Red LED indicator: :100V output
Yellow LED indicator: Completed
CHARGE③
Red LED indicator: in process of charging
Measurement time : 10sec, 30sec, 60sec
Range : Can be set up the max and min of measurement value (by 0.5 exponent)
（１０ ）Accuracy : ±0.5 decade ex.
８５±０５
..
Measurement volatage : Automatically adjust/chamge
Cube of 3 to 6 : 10V, 10mA max①
Cube of 6 to 13 : 100V, 1mA max②
Source : Inside battery
External outlet : External probe connector①
AC adaptor connector (battery charging USB mini type)②
Measurement are : 50mm probe length ×50mm (probe distance) (in measurement)（）
Probe material : Special conductive rubber (volume resistivity 0.02Ω max.)･㎝
Environment : 15 25 under 60%R.H.℃〜 ℃，
Dimension : 114(W)×78(D)×69(H) max. (mm)
Case : Stainless
Weight : body 700g
cable 25g
−−page 5
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