IET Labs 1404 Series User manual

¨PRECISION INSTRUMENTS FOR TEST AND MEASUREMENT ¨
Email: inf[email protected]
TEL: [phone] • FAX: [phone]
www.ietlabs.com
IET LABS, INC.
1404 Series
Primary Capacitance Standard
Operation Manual
Copyright © 2022 IET Labs, Inc.
Visit www.ietlabs.com for manual revision updates
1404 im/May 2022

¨PRECISION INSTRUMENTS FOR TEST AND MEASUREMENT ¨
Email: inf[email protected]
TEL: [phone] • FAX: [phone]
www.ietlabs.com
IET LABS, INC.

WARRANTY
We warrant that this product is free from defects in material and workmanship and, when properly used,
will perform in accordance with applicable IET specifications. If within one year after original shipment,
it is found not to meet this standard, it will be repaired or, at the option of IET, replaced at no charge when
returned to IET. Changes in this product not approved by IET or application of voltages or currents greater
than those allowed by the specifications shall void this warranty. IET shall not be liable for any indirect,
special, or consequential damages, even if notice has been given to the possibility of such damages.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED,
INCLUDING BUT NOT LIMITED TO, ANY IMPLIED WARRANTY OF MERCHANTABILITY OR
FITNESS FOR ANY PARTICULAR PURPOSE.
i

Safety Symbols
General definitions of safety symbols used on the instrument or in manuals are listed below.
Caution symbol: the product is marked with this symbol when it is necessary for the user to
refer to the instruction manual.
Hazardous voltage symbol: the product is marked with this symbol when high voltage maybe
present on the product and an electrical shock hazard can exist.
Indicates the grounding protect terminal, which is used to prevent electric shock from the
leakage on chassis. The ground terminal must connect to earth before using the product
Direct current.
Alternating current.
Frame or chassis terminal. A connection to the frame (chassis) of the equipment which
normally includes all exposed metal structures.
On supply.
Off supply.
Hot surface. Avoid contact. Surfaces are hot and may cause personal injury if touched.
Disposal
Waste Electrical and Electronic Equipment (WEEE) Directive 2002/96/EC
This product complies with the WEEE Directive (2002/96/EC) marking requirements.
The affixed label indicates that you must not discard this electrical/ electronic product in domestic
household waste.
Product Category: With reference to the equipment types in the WEEE directive Annex 1, this product
is classified as a “Monitoring and Control instrumentation” product.
Do not dispose of electrical appliances as unsorted municipal waste, use separate collection facilities.
Contact your local government for information regarding the collection systems available. If electrical
appliances are disposed of in landfills or dumps, hazardous substances can leak into the groundwater
and get into the food chain, damaging your health and well-being.
When replacing old appliances with new one, the retailer is legally obligated to take back your old ap-
pliances for disposal.
Proposition 65 Warning for California Residents
WARNING: Cancer and Reproductive Harm - www.P65Warnings.ca.gov.
This product may contain chemicals known to the State of California to cause cancer, birth defects, or
other reproductive harm

SAFETY PRECAUTIONS
The following general safety precautions must be observed during all phases of operation, service, and repair of
this instrument. Failure to comply with these precautions or with specific WARNINGS elsewhere in this manual
may impair the protection provided by the equipment. Such noncompliance would also violate safety standards
of design, manufacture, and intended use of the instrument.
IET Labs assumes no liability for the customer’s failure to comply with these precautions.
If an instrument is marked CAT I (IEC Measurement Category I), or it is not marked with a measurement category,
its measurement terminals must not be connected to line-voltage mains.
The 1404 is an indoor use product.
DANGEROUS PROCEDURE WARNINGS
Comply with all WARNINGS - Procedures throughout in this manual and instructions on the instrument prevent
you from potential hazard. These instructions contained in the warnings must be followed.
CAUTION
• DO NOT Operate in an Explosive Atmosphere
• Do not operate the instrument in the presence of inflammable gasses or fumes
• Operation of any electrical instrument in such an environment clearly constitutes a safety hazard
• Use Caution around live circuits and whenever hazardous voltages > 45 V are present
• Operators must not remove instrument covers
• Component replacement and internal adjustments must be made by qualified maintenance personnel only
• DO NOT substitute parts or modify the instrument
• When working with high voltages; post warning signs, train personnel and keep unauthorized personnel away.
Do not apply any voltage or currents to the terminals of the instrument in excess of the maximum limits
indicated in the specifications section of this manual.
To avoid the danger of introducing additional hazards, do not install substitute parts or perform unauthorized
modifications to the instrument.
Return the instrument to an IET Labs for service and repair to ensure that safety features are maintained in
operational condition.

WARNING
OBSERVE ALL SAFETY RULES
WHEN WORKING WITH HIGH VOLTAGES OR LINE VOLTAGES.
Dangerous voltages may be present inside this instrument. Do not open the case
Refer servicing to qualified personnel
HIGH VOLTAGES MAY BE PRESENT AT THE TERMINALS OF THIS INSTRUMENT
WHENEVER HAZARDOUS VOLTAGES (> 45 V) ARE USED, TAKE ALL MEASURES TO
AVOID ACCIDENTAL CONTACT WITH ANY LIVE COMPONENTS.
USE MAXIMUM INSULATION AND MINIMIZE THE USE OF BARE
CONDUCTORS WHEN USING THIS INSTRUMENT.
Use extreme caution when working with bare conductors or bus bars.
WHEN WORKING WITH HIGH VOLTAGES, POST WARNING SIGNS AND
KEEP UNREQUIRED PERSONNEL SAFELY AWAY.
CAUTION
DO NOT APPLY ANY VOLTAGES OR CURRENTS TO THE TERMINALS OF THIS
INSTRUMENT IN EXCESS OF THE MAXIMUM LIMITS INDICATED ON
THE FRONT PANEL OR THE OPERATING GUIDE LABEL.
iv

Contents
Chapter 1 Introduction ..............................................................................1
1.1 Description of the 1404 Series.............................................................................. 1
Chapter 2 Specifications ...........................................................................2
Speci!cations ................................................................................................................ 2
Chapter 3 Operation ..................................................................................5
3.1 Initial Inspection and Setup .................................................................................. 5
3.2 Connections to Capacitor...................................................................................... 5
3.3 Temperature Coe"cient........................................................................................ 5
3.4 Temperature Cycling............................................................................................. 6
3.5 Design ................................................................................................................... 6
3.6 Environmental Conditions .................................................................................... 6
3.6.1 Operating Temperature ............................................................................... 6
3.6.2 Storage Temperature ................................................................................... 6
3.7 Shipping and Handling ......................................................................................... 6
Chapter 4 Maintenance..............................................................................7
4.1 Preventive Maintenance........................................................................................ 7
4.2 Calibration............................................................................................................. 7
4.2.1 Calibration Interval..................................................................................... 7
4.2.2 General Considerations............................................................................... 7
4.2.3 Calibration Procedure ................................................................................. 7
4.4 Calibration with GenRad 1620 or AH2500A........................................................ 8
4.5 Replaceable Parts List........................................................................................... 9
v

vi

1
1404 Series
1Introduction
Chapter 1
INTRODUCTION
1.1 Description of the 1404 Series
The 1404 Series (Figure 1-1) are stable, pri-
mary laboratory pacitance standards. They are
working and laboratory standards grade. The
1404 units are available in values ranging from
10 pF to 10 nF with custom values available.
All critical parts of the plate assembly are made of
invar for stability and low temperature coe•cient.
After heat cycling and adjustment the assembly is
mounted in a heavy brass container, which after
evacuation, is •lled with dry nitrogen under pressure
slightly above atmospheric and sealed. The container
is mounted on an aluminum panel and protected by
an outer aluminum case. Each capacitor is subjected
to a series of temperature cycles to determine hys-
teresis and temperature coe•cients and to stabilize
the capacitance.
Connections are made to the 1404 via two bnc connec-
tors to minimize lead stray capacitance. Traditional
GenRad 874 connectors are also available upon
request.
Figure 1-1: 1404-A Primary Capacitance
Standard
Figure 1-2: 1404-10nF shown next to
standard 1404-A

2
1404 Series
2 Specifications
Chapter 2
SPECIFICATIONS
For convenience to the user, the pertinent specifications are given in a label, shown in Figure 2-1 affixed to the
case of the instrument.
1404-9701 1404-A, 1000 pF
1404-9702 1404-B, 100 pF
1404-9703 1404-C, 10 pF
1404-5nF 1404-A, 5 nF
1404-10nF 1404-A, 10 nF
ORDERING INFORMATION
SPECIFICATIONS
Model Calibration
Uncertainty
Adjustment
Accuracy Short Term Drift Long Term Drift Max Change with Orientation Maximum Voltage Dissipation Factor
1404-A
1404-B
1404-C
< ±6 ppm
±5 ppm to a ca-
pacitance about 5 ppm
above the nominal
value
less than 2 ppm less than 20 ppm per year 10 ppm and completely
reversible 750 V peak < 10-5 at 1 kHz
1404-5 nF
1404-10 nF ±100 ppm ±500 ppm less than 12 ppm less than 40 ppm per year 15 ppm and completely
reversible 100V peak < 10-5 at 1 kHz
Calibration: An A2LA certificate of calibration is supplied with each
capacitor, giving the measured direct capacitance at 1 kHz, 30 Vac
and 23° ±1°C.
Temperature Coefficient of Capacitance: A measured value with
and accuracy of ±1 ppm/°C is given on the certificate.
Model Temperature Coefficient
1404-A
1404-B 2 ±2 ppm/°C from -20°C to +65°C
1404-C 5 ±2 ppm/°C from -20°C to +65°C
1404-5 nF
1404-10 nF 4 ±6 ppm/°C from -20°C to +65°C
Temperature Cycling: For temperature cycling over range from
-20°C to +65°C , hysteresis (retraceable) is less than 20 ppm at
23°C.
Residual Impedance:
Model CHCLL
1404-A
1404-B
1404-C
30 pF 28 pF 0.05 µH
Model CHCLL
1404-5 nF
1404-10 nF 130 pF 127 pF 0.1 µH
Terminals: Two BNC coaxial connectors (legacy locking G874
coaxial connectors are available). Outer shell of one connec-
tor is ungrounded to permit capacitor to be used with external
resistor as a dissipation factor standard.
Mechanical:
Model Dimensions Weight
1404-A
1404-B
1404-C
(16.9 cm H x 17.2 cm W x 20.4 cm D
(6.63" x 6.75" x 8")
3.9 kg 8.5 lb
6.4 kg 14 lb Shipping
1404-5 nF
1404-10 nF
(23 cm W x 23 cm H x 22 cm D)
9" x 9" x 8.5"
16 kg 35 lb
18 kg 40 lb Shipping

3
1404 Series
3Specifications
Calibration: At 1 kHz, 1.5 Vac, at 23oC
Stability: Long term drift is less than 20 ppm per year, typically
much smaller. Maximum change with orientation is 10 ppm and
is completely reversible.
Temperature Coefficient of Capacitance: 2 ±2 ppm/oC, from
-20oC to +65oC.
Dissipation Factor: < 10-5 at 1 kHz.
Residual Impedances: See the figure for typical values of internal
series inductances and terminal capacitances.
Max Voltage: 750 V.
Terminals: Two BNC (standard) or GR 874 connectors; easily
convertible to other types of connectors by attachment of locking
adaptors. Outer shell of one connector is ungrounded to permit
capacitor to be used with external resistor as a dissipation factor
standard.
STANDARD REFERENCE CAPACITOR
Model 1404-A 1000 pF
Observe all safety rules when working with high voltages or line voltages.Connect the shield to earth ground in order to maintain
the case at a safe voltage. Whenever hazardous voltages (>45 V) are used, take all measures to avoid accidental contact with
any live components: a) Use maximum insulation and minimize the use of bare conductors. b) Remove power when adjusting
the capacitor. c) Post warning signs and keep personnel safely away.
Equivalent circuit showing direct
capacitance CD, and typical
values of residual inductance, L,
and terminal capacitances, CH,
and CL.
1000 pF
IET LABS, INC. 1404 lbl/1000 pF/p1/02-20-19
GenRad
formerly manufactured by
• Email: [email protected]
• Tel: [phone] • www.ietlabs.com
SN: D7-21401487
Date 5/11/2022
Frequency 1 kHz
Capacitance (pF) 1000.0044
Meas. Uncertainty 5.5 ppm
Dissipation 0.000002
Tempco (ppm/C) -0.160 ppm/C
Test Conditions 23.2 C
33% RH
Recommended Due
By CN
Figure 2-1: Sample label attached to an 1404 unit

4
1404 Series
4 Specifications

5
1404 Series
5Operation
Chapter 3
OPERATION
3.1 Initial Inspection and Setup
This instrument was carefully inspected before ship-
ment. It should be in proper electrical and mechanical
order upon receipt.
To provide ready reference to specifications, a label,
shown in Figure 2-1, is attached to the case of the
instrument.
3.2 Connections to Capacitor
All 1404 capacitors have 2 bnc connectors labeled
HI and LO, as shown in figure 3-1.
Figure 3-1: 1404 capacitor standard with bnc
connectors
Equivalent circuit showing direct capacitance, CD,
and average values of residual inductance, L, and
terminal capacitances, CHand CL. See specifica-
tions for values of residuals
.
Figure 3-2: Capacitance shunted by leakage
to case
3.3 Temperature Coefficient
Temperature coefficients are given on the certificate
of calibration and the label attached to the standards.
It is important to consider the TC of the 1404 when
measuring at temperatures other than 23°C.

6
1404 Series
6 Maintenance
3.4 Temperature Cycling
The 1404 series can be used over a wide temperature
range however it is important to understand that
hysteresis (retrace) can cause errors of up to 20 ppm.
When a standard is subjected to relatively large tem-
perature changes, such as shipment, the calibrated
capacitance value may come back to a different
calibrated value at the same temperature after it has
been exposed to hot or cold conditions, this is called
hysteresis or retrace.
The 1404 Standard Capacitor utilizes invar plates and
spacers to minimize the effects of thermal expansion.
The standard should be keep in temperature condi-
tions close to 23°C ±1°C to minimize the error due
to hysteresis.
3.5 Design of the 1404
The 1404 is a three-terminal standard air capacitor.
The invar plates that make up the capacitor are her-
metically sealed in a can, filled with dry nitrogen to
minimize effects of both humidity and barometric
pressure.
The 1404 capacitors show very small changes with
orientation however this can be minimized by keeping
the 1404 in the upright orientation which is how it is
calibrated at IET Labs.
Additional information on the design of the 1404 can
be found at;
https://www.ietlabs.com/pdf/GR_
Experimenters/1963/GenRad_Experimenter_
Aug_1963.pdf
3.6 Environmental Conditions
3.6.1 Operating Temperature
For optimal accuracy, 1404 models should be used
in an environment of 23°C ±1°C. They should be
allowed to stabilize at those temperatures after any
significant temperature variation.
3.6.2 Storage Temperature
The 1404 units should be maintained within the stor-
age temperature range of 0°C to 40°C to retain its
accuracy within the specified limits.
3.7 Shipping and Handling
The 1404 Series should not be exposed to any excessive
shock or temperature extremes.

7
1404 Series
7Maintenance
Chapter 4
MAINTENANCE
4.1 Preventive Maintenance
Keep the unit in a clean environment. This will help
prevent possible contamination.
1404’s are packaged in a closed case, which limits the
entry of contaminants and dust into the instruments.
If they are maintained in a clean or air-conditioned
environment, cleaning will seldom be required. In a
contaminated atmosphere, cleaning may be required.
4.2 Calibration
The 1404 units may be employed as stand-alone
instruments or as integral components of a system.
If used as part of a system, they should be calibrated
as part of the overall system to provide an optimum
system calibration.
4.2.1 Calibration Interval
The recommended 1404 Series calibration interval is
twelve (12) months.
The calibration procedure may be carried out by the
user if a calibration capability is available, by IET
Labs, or by a certified calibration laboratory.
If the user should choose to perform this procedure,
then the considerations below should be observed.
4.2.2 General Considerations
It is important, whenever calibrating an 1404 unit, to
be very aware of the capabilities and limitations of
the test instruments used.
Recommended Instruments:
• Andeen and Hagerling AH2500A
or
• IET Model 1620 or 1621 Precision
Capacitance Measurement System (bridge)
It is important to allow both the testing instrument
and the 1404 to stabilize for a number of hours at the
nominal operating temperature of 23OC, and at nomi-
nal laboratory conditions of humidity. There should
be no temperature gradients across the unit under test.

8
1404 Series
8 Maintenance
4.3 Calibration Procedure with
GenRad 1620 or AH2500A/
AH2700A Capacitance Bridge
To calibrate an 1404 unit, proceed as follows:
1. 1404 capacitors with bnc connectors should
have the shield disconnected at the HI termi-
nal to minimize stray capacitance. The shield
on the LO terminal should be maintained.
This connection mimics the connection on the
IET/GenRad 1404 Standard Capacitor.
2. Determine and employ proper metrological
practices.
Allow a confidence band for the uncer-
tainty of the measuring instrument and
setup.
3. Determine the allowable drift limits for the
capacitance reading.
<20 ppm/year
4. Confirm that the readings fall within these
drift limits, allowing for the uncertainty band.
If the reading falls outside the limits,
it has to be repaired by IET or another
qualified facility

9
1404 Series
9Maintenance
4.4 Replaceable Parts List
There are no replaceable parts on the 1404 Series.
Contact IET Labs at for an RMA should service be
required at:
https://www.ietlabs.com/