Atec Megger-220072 - Manual (Page 2)

70-, 120- and 160-kV DC
High Voltage DC Dielectric Test Sets
Time-varying tests such as the polarization index test (PI
test) are independent of temperature effects and save time.
To perform this test, a predetermined test voltage is
applied to the unit under test and readings are taken at 1
minute and 10 minutes. The resulting ratio is analyzed to
determine insulation quality. This type of test is especially
appropriate for high-capacitance samples.
The step-voltage test is independent of temperature effects
and saves time. To perform this test, the output voltage is
increased in even steps at regular intervals over a fixed
period of time. As long as the resistance of the unit under
test increases with time, it has high-quality insulation. This
type of test is only useful for high-capacitance samples.
FEATURES AND BENEFITS
Operates Like a Full-Wave Rectified Unit
(Filtered Half-Wave Rectification)
■ Provides the advanced performance equal to a
full-wave rectified unit.
■ Allows for a simple circuit scheme for long-term
reliability.
Lightweight High-Voltage Module
■ Air insulated, it is the lightest weight module available
for its voltage and power ratings.
■ Convenient portability allows a single operator to
transport it into the field.
Complete Internal Guard Circuit/Guard
Connection on High-Voltage Output Cable
■ Intercepts stray surface leakage currents which could
interfere with the measurement.
■ Eliminates the need for an extra lead to hook up the
guard connection.
■ Ensures highly accurate measurements.
Choice of Digital or Analog Metering
■ The preferred medium may be selected by the user.
Continuously Variable Test Voltage
■ User can set test voltage to intermediate values
as required.
Fast Charging of High-Capacitance Samples
■ Saves the operator test time.
Negative Polarity to Ground
■ Applies a worst-case condition to assure reliability.
Strip Chart Recorder (Optionally Available)
■ Provides a permanent record of the leakage current for
the unit under test.
Standard Safety Features
■ Bipolar ammeter that displays the magnitude of
the discharge current from the unit under test
(digital
models only)
■ Input-supply-line circuit breaker
■ Output current overload relay
■ Zero-start interlock for high-voltage output
■ Pushbutton controls and indicating lights for
high-voltage ON/OFF
■ Full circuit-breaker protection against internal damage
by overloads, surges or test sample breakdown
■ Connection for external permissive and safety interlocks
Model Capabilities/Applications
Following are the acceptance and maintenance
testing capabilities of each of the dc dielectric test
sets.
70-kV DC Dielectric Test Set
■ Acceptance testing on 15 kV class cable
■ Maintenance testing on 28 kV class cable
120-kV DC Dielectric Test Set
■ Acceptance testing on 35 kV class cable
■ Maintenance testing on 46 kV class cable
160-kV DC Dielectric Test Set
■ Acceptance testing on 46 kV class cable
■ Maintenance testing on 115 kV class cable
SPECIFICATIONS
Input Power
Nominal 120 Vac, 50/60 Hz
For 220/240 Vac, 50/60-Hz operation, add –47 to Cat. No.
Please note that specifications for the –47 models differ as
follows:
Output Current: 220/240 Vac
120 kV Models: 5 mA for 5 min; 2 mA continuous
160 kV Models: 5 mA for 5 min; 1.5 mA continuous
When using external 240/120-volt step-down voltage transformers,
the ratings may be used as given for 120 volt input.
Weight: Add approx 2 lb (1 kg) for –47 control unit.
Ammeter (Digital Models)
Ranges:
0 to 19.9 µA
0 to 199 µA
0 to 1.99 mA
0 to 5 mA
Resolution: To 0.1 µA on lowest range
Accuracy: ±2% of reading + 1 digit
Ammeter (Analog Models)
Ranges:
0 to 5 µA
0 to 50 µA
0 to 500 mA
0 to 5 mA
Resolution: To 0.1 µA on lowest range
Accuracy: ±2% of full scale range
Voltmeter (Digital Models)
Resolution: To 100 V over entire range
Accuracy: ±(2% of reading + 100 V)
Voltmeter (Analog Models)
Resolution — Dual Range:
35 kV/70 kV: 2.5% full scale
60 kV/120 kV: 1.6% full scale
80 kV/160 kV: 2.5% full scale
Accuracy: ±2% of full scale range