Cal Test Electronics CT4026 User manual

CT4026

User Manual

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Safety Summary

WARNING CAUTION

To avoid personal injury and/or product damage, review and comply

with the following safety precautions. These precautions apply to both
operating and maintenance personnel and must be followed during all
phases of operation, service, and repair of this instrument.

Only qualied personnel should use this probe. This high voltage
probe is designed to be used by personnel who are trained, experienced,

or otherwise qualied to recognize hazardous situations and who are

trained in the safety precautions necessary to avoid possible injury when
using such a device.

This instrument is intended for usage within Measurement Category I
(CAT I) only.

Do not work alone when working with high voltages.

Do not apply to the input any potential that exceeds the maximum
rating of the probe.

For your own safety, inspect the probes for cracks and frayed or broken

leads before each use. If defects are noted, DO NOT USE the probe.

Hands, shoes, oor and work bench must be dry.

Avoid making measurements under humidity, dampness or other

environmental conditions that might affect safety.

Turn the high voltage source off before connecting or disconnecting
the probe whenever possible.

The probe body should be kept clean and free of any conductive
contamination.

Do not remove the probe casing. Removal of the probe’s casing may
expose you to electric shock.

Keep ngers behind the probe’s nger guard during use.

Always properly ground the probe with the lead before contacting high

voltage circuits with the probe tip. Always disconnect the probe tip from

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high voltage circuits before disconnecting the ground lead. Do not connect
the probe ground lead to any point which is at a potential other than earth
ground.

Use only on test instruments where the chassis or return lead is
properly grounded.

Use only in ofce-type indoor setting

z The instrument is designed to be used in office-type indoor

environments. Do not operate the instrument:

z In the presence of noxious, corrosive, or flammable fumes,

gases, vapors, chemicals, or finely-divided particulates.

z In environments where there is a danger of any liquid being

spilled on the instrument.

z In air temperatures exceeding the specified operating

temperatures.

z In atmospheric pressures outside the specified altitude limits or

where the surrounding gas is not air.

Use in an indoor Pollution Degree 2 environment. Measurements made

by this instrument may be outside specications if the instrument is used
in non-ofce-type environments. Such environments may include rapid

temperature or humidity changes, sunlight, vibration and/or mechanical

shocks, acoustic noise, electrical noise, strong electric elds, or strong
magnetic elds.

Not for critical applications. This instrument is not authorized for use in

contact with the human body or for use as a component in a life-support
device or system.

Hazardous voltages may be present in unexpected locations in
circuitry being tested when a fault condition in the circuit exists.

Do not substitute parts that are not approved by Cal Test Electronics
or modify this instrument. Return the instrument to Cal Test Electronics
for service and repair to ensure that safety and performance features are
maintained.

WARNING statement calls attention to an operating procedure,

A
practice, or condition, which, if not followed correctly, could result in injury

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or death to personnel.

A

CAUTION statement calls attention to an operating procedure, practice,

or condition, which, if not followed correctly, could result in damage to or
destruction of parts or the entire product.

Compliance Statements

Disposal of Old Electrical & Electronic Equipment

(Applicable in the European Union and other European
countries with separate collection systems). This product is
subject to Directive 2012/19/EU of the European Parliament
and the Council of the European Union on waste electrical
and electronic equipment (WEEE), and in jurisdictions
adopting that Directive, is marked as being put on the market
after August 13, 2005, and should not be disposed of as

unsorted municipal waste. Please utilize your local WEEE

collection facilities in the disposition of this product and

otherwise observe all applicable requirements.

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1 Introduction

Overview

The Cal Test CT4026 is an 18 kV High Voltage divider probe for use
with both digital and analog oscilloscopes.

Features

z Measures up to: 18 kV (DC + ACpk) or 12 kVrms AC
z DC to 150 MHz bandwidth
z Voltage dividing of 1000:1
z Frequency compensation

Probe Accessories

Figure 1: CT4026 Probe Accessories

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1. Standard Probe Tip

2. Hands-Free Hook Probe Tip

3. Hands-Free Bolt-On Probe Tip

4. Grounding Lead Extension Cable

5. Grounding Alligator Clip

6. Trimmer Tool

7. BNC Cable

8. Frequency Compensation Trimmer

9. Main Grounding Lead

2 Using the Probe

1. Connect the probe to the BNC input of the oscilloscope.

2. On the oscilloscope, select the desired volts/division range.
Whenever available, set the probe attenuation ratio setting to 100:1.

3.

WARNING If possible, always turn the high voltage source off

before connecting or disconnecting the probe.

4. WARNING Connect the probe grounding lead (via alligator clip) to
a good earth ground or reliable chassis ground.

5. For the best frequency response, when measuring frequencies

> 40 MHz use only the Main Grounding Lead plus the Grounding
Alligator Clip. (Figure 1). For frequencies < 40 MHz the Grounding

Lead Extension Cable may be used and will give you better reach with
the probe.

WARNING Before turning on the high voltage source, be certain

6.
the operator is not touching any part of the device under test.

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7. Turn on the high voltage source.

8. You will now be able to analyze the voltage waveform on your

oscilloscope.

9. Turn off the high voltage source.

10.

WARNING Disconnect the probe from the high voltage source

BEFORE disconnecting the ground clip lead.

3 Frequency Compensation

Proper compensation of the probe is required to assure amplitude
accuracy of the waveform being measured by matching the probe to
the oscilloscope’s input capacitance. Compensation should be adjusted
whenever the probe is connected to, or transferred between, oscilloscopes.

The procedure is the same as for a x10 passive probe.

200 Hz Adjustment

1. Connect the probe to the oscilloscope.

2. Apply a 200 Hz square wave to the probe tip and adjust the

oscilloscope controls to display a few cycles of the waveform.

3. Turn the 200 Hz Trimmer (Figure 2) using the Trimmer Tool,

making a at topped square wave (Figure 4).

Figure 2: Frequency Compensation Trimmer

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200 kHz and Bandwidth Adjustments

4. CAUTION 200 kHz and bandwidth adjustments should only be
made by a quali ed engineer. Remove the plastic cover to access

these trimmers.

5. Change the square wave output to 200 kHz or to the frequency you

will be using in your testing.

6. Turn the 200 kHz Trimmer for a  at topped square wave (Figures 2

& 4).

7. Turn the Bandwidth Trimmer for tuning the probe’s bandwidth
(Figure 2).

Figure 3 shows how over- and under-compensated pulse responses
will look.

Figure 3: Over/Under Compensation

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Figure 4 shows a perfectly compensated probe.

Figure 4: Good Compensation

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4 Specications

All specications apply to the unit after a temperature stabilization time

of 15 minutes over an ambient temperature range of 25 °C ± 5 °C.

CT4026 Specications

Maximum Input Voltage

(CAT I)

Maximum Loading

Current

Division Ratio 1000:1

Bandwidth DC to 150 MHz

Compensation Range 10 pF to 35 pF

Temperature Coefcient ≤200 ppm/ºC

Input Resistance 200 MΩ

Input Capacitance 1.5 pF

Rise Time 2.4 ns

Signal/Noise

Accuracy: DC Volts ≤3%

Accuracy: AC Volts ≤3% at 1 kHz

Cable Length

Designed for Use in

Operating Environment

Storage Temperature

Humidity

Dimensions

Weight

Warranty

≤85% relative humidity at 95ºF (35ºC)

18 kV (DC + ACpk)

12 kVrms AC

90 µA

>60 dB @ 1 KHz
>50 dB @ 1 MHz

6.6 ft (2 m)

Pollution Degree 2

14ºF to 131ºF (-10ºC to 55ºC)

-4ºF to 158ºF (-20ºC to 70ºC)

3.1 x 3.1 x 12.6 in
(8 x 8 x 32 cm)

1.0 lbs (460 g)

One-year warranty

Specications are subject to change without notice.

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5 Voltage Derating Curve

WARNING

When measuring higher frequency signals, be sure to comply with the
Voltage vs Frequency Derating Curve.

Figure 5: Voltage Derating Curve

6 Cleaning

Clean only the exterior probe body and cables. Use a soft cotton cloth
lightly moistened with a mild solution of detergent and water. Do not
allow any portion of the probe to be submerged at any time.

WARNING

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Dry the probe thoroughly before attempting to make voltage
measurements.

CAUTION Do not subject the probe to solvents or solvent fumes as

these can cause deterioration of the probe body and cables.

7 Service & Warranty Information

Limited One-Year Warranty

Cal Test Electronics warrants this product to be free from defective
material or workmanship for a period of 1 year from the date of original
purchase. Under this warranty, Cal Test Electronics is limited to
repairing the defective device when returned to the factory, shipping
charges prepaid, within the warranty period.

Units returned to Cal Test Electronics that have been subject to abuse,
misuse, damage, or accident, or have been connected, installed, or
adjusted contrary to the instructions furnished by Cal Test Electronics,

or that have been repaired by unauthorized persons, will not be

covered by this warranty.

Cal Test Electronics reserves the right to discontinue models, change

specications, price, or design of this device at any time without notice

and without incurring any obligation whatsoever.

The purchaser agrees to assume all liabilities for any damages and/or
bodily injury which may result from the use or misuse of this device by
the purchaser, his employees, or agents.

This warranty is in lieu of all other representations or warranties
expressed or implied and no agent or representative of Cal Test

Electronics is authorized to assume any other obligation in connection

with the sale and purchase of this device.

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