SCREENING EFFICIENCY TESTER
Measures the screening efficiency of conductive suits worn by
live working maintenance personnel on power transmission lines.
Features:
• 3 screening efficiency indicators:
results presented as POOR, MARGINAL EFFECTIVE or GOOD
bar-graph digital reading in -db
• 5kHz, 400VAC transmitter
• Simple, quick
Self-calibrating process
• Field and laboratory use
Battery powered
Rugged construction
Dust/waterproof carrying case
Applications:
Conductive suits are worn by service personnel while performing live working maintenance on
power transmission lines and in substations. The suits are designed to shield personnel from
low frequency electric fields emitted by the live parts. During the life of the suit the conductive
fibers woven into the fabric begin to breakdown due to repeated laundering, and wear and tear
in areas such as the seat, knees and elbows, thus slowly reducing the effective protection
afforded to the wearer. The ability of the suit fabric to provide a shield for the wearer from
these electric fields is a fabric property commonly referred to as “screening efficiency”.
The ETS Model 271 Screening Efficiency Tester is a portable, battery-powered, instrument
designed to accurately measure the screening efficiency in decibels (-db) in both field and
laboratory environments. It performs nondestructive testing on any section of suit or test fabric
that is at least 4” (10cm) in diameter. The higher the absolute reading the better the screening
efficiency or conductivity of the fabric and thus lower the magnitude of the electric field on the
wearer side of the fabric.
Description:
The Model 271 Screening Efficiency Tester is a completely integrated, microcomputer-based
instrument for laboratory and field use. The Tester consists of a 5 kHz, 400VAC transmitter
plus a nesting receiver that contains the control, detection, processing, and display functions
plus batteries. Both transmitter and receiver are contained in rugged aluminum housings, 4”
(10cm) in diameter x 1.5” (3.8cm) and x 3.375” (8.6cm) respectively. The two units are
connected by a 24” (60cm) cable. Measurements can be taken at virtually any non-seam
location on the suit.
The Model 271 has better than -70db, of dynamic range (-18.1db to -91.9db). A 2-line alphanumeric
LCD display indicates the electric field strength with a bar-graph and interpretation of
the signal as to whether the material is a POOR, MARGINAL, EFFECTIVE or GOOD shield.
After approximately 2 sec. the actual screening efficiency is then displayed in -db. The
instrument is self-calibrating. Prior to each test session the CAL button is momentarily
depressed which calibrates the system. Performance is easily checked by first taking a
measurement without fabric between the transmitter/receiver (-18db) and then with aluminum
foil between the transmitter/receiver (-90db).
To measure a suit or test fabric, the desired section is placed between the transmitter/receiver.
Prompts on the display walk the user through the measurement process. Each time the TEST
button is depressed the triple indication will appear on the LCD display. The system is
defaulted to define a fabric that has a screening efficiency greater than -50db to be considered
GOOD, between -40 and -50db, EFFECTIVE, between -30 and -40db, MARGINAL and below
-30db, POOR. Other default settings can be programmed as an option. The Model 271 may
also be used for other applications where the screening efficiency of conductive fabric or thin
films need to be evaluated.
The Model 271 Screening Efficiency Tester comes complete with transmitter/receiver, 2 spare
9V alkaline batteries, operating manual plus a dust/waterproof ABS carrying case.
Specifications:
Transmitter:
Frequency: 5 kHz
Voltage: 400VAC, p-p
Electrode: Concentric ring
Receiver: Power:
Dynamic range: <-18.1 to-91.9db
Controls: ON/OFF, TEST, CAL
Display: 2-line, LCD alpha-numeric
Calibration: Direct injection of xmitter
signal attenuated by 20±.5db
Dimensions:
Case: 10.8”x9.85”x4.5”
(27.5x25x11.5cm)
Weight: 5 lbs (2.2kg)
Power:
Batteries: 2x9V Alkaline
Life: Approx. 500 tests
Indication: “Low Battery”
Warranty:
One (1) Year
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