Keithley 7154 User manual

Model 7154
2-Pole High Voltage Scanner Card
Instruction Manual
Contains Operating and Servicing Information

WARRANTY

Model 7154 2-Pole High Voltage
Scanner Card
instruction Manual
B 1988, Kcithlcy Instruments, Inc.
Test Instrumentation Croup
All rights reserved.
Cleveland, Ohio, U.S.A.
March 1988, First Printing
document Numhcr: 7154-901-01 Rev. A

SAFETY PRECAUTIONS
The following safety precautions should be observed before using this
product and any associated instrumentation. Although some instruments
and accessories would normally be used with non-hazardous voltages,
there are situations where hazardous conditions may be present.
This product is intended for use by qualified personnel who recognize
shock hazards and are familiar with the safety precaution8 required to
avoid possible injury. Read the operating information carefully before us-
ing the product.
Exercise extreme caution when a shock hazard is present. Lethal voltage
may be present on cable connector jacks or test fixtures. The American
National Standards Institute (ANSI) states that a shock hazard exists
when voltage levels greater than 30V RMS, 42.4V peak, or 60VDC are
present. A good safety practice is to expect that hazardous voltage is
present in any unknown circuit before measuring.
Before operating an instrument, make pure the line cord is connected to a
properly grounded power receptacle. Inspect the connecting cables, test
leads, and jumpers for possible wear, cracks, or breaks before each use.
For maximum safety, do not touch the product, test cables, or any other
instruments while power is applied to the circuit under test. ALWAYS re-
move power from the entire test system and discharge any capacitors be-
fore: connecting or disconnecting cables or jumpers, installing or
removing switching cards, or making internal changes, such as installing
or removing jumpers.
Do not touch any object that could provide a current path to the common
side of the circuit under test or power line (earth) ground. Always make
mcasurcmcnts with dry hands while standing on a dry, insulated surface
capable of withstanding the voltage being measured.
Do not exceed the maximum signal levels of the instruments and acces-
sories, as defined in the specifications and operating information, and as
shown on the instrument or test fixture rear panel, or switching card.
Do not connect switching cards directly to unlimited power circuits. They
arc intended to be used with impedance limited sources. NEVER connect
switching cards directly to AC main. When connecting sources to switch-
ing cards, install protective devices to limit fault current and voltage to
the card.

When fuses are used in a product, replace with same type and rating for
continued protection against fire hazard.
Chassis connections must only be used as shield connections for rneasur-
ing circuits, NOT as safety earth ground conncctionfi.
If you are using a test fixture, keep the lid closed while power is applied
to the device under test. Safe operation requires the use of a lid interlock.
If a @ screw is present on the test fixture, connect it to safety earth
ground using #18 AWG or larger wire.
The $ symbol on an instrument or accessory indicates that 1OOOVor
more may be present on the terminals. Refer to the product manual for de-
tailed operating information.
Instrumentation and accessories should not be connected to humans.
Maintenance should be performed by qualified service personnel. Before
performing any maintenance, disconncct the line cord and all test cables.

SPECIFICATIONS
CHANNELS PER CARD: 10.
CONTACT CONFIGURATION: Z-pole Form A with
user selectable shield or driven guard. Each pole is
fused using No. 38 AWG magnet wire.
CONNECTOR TYPE: Screw terminals, No. 16 AWG
maximum.
RELAY DRIVE CURRENT: 57mA per relay typical.
MAXIMUM SIGNAL LEVEL: 1lOOV peak, 0.5A nns
switched, 1.OA rms carry, 1OVA (resistive load only).
CONTACT LIFE: >lO”closures (cold switching); >5 x 10‘
closures (at maximum signal levels).
CONTACT RESISTANCE: <2WmQ initial, 2n to rated
life.
CONTACT POTENTIAL: <35pV per contact pair with
copper leads.
ACTUATION TIME <2ms, exclusive of mainframe.
CHANNEL ISOLATION: >lO’“fl, <lOpF.
INPUT ISOLATION:
Differential: >lOQ, c50pF.
Common Mode: >lOQ <150pF.
COMMON MODE VOLTAGE: 1lOOV peak.
OPERATING ENVIRONMENT: 0’ to 50°C; up to 35°C
at 70% R.H.
STORAGE ENVIRONMENT: -25O to +65OC.
DIMENSIONS, WEIGHT: 32mm high x 114mm wide x
272mm long (l-l/4 in. x 4-l/2 in. X lo-3/4 in.). Net
weight 0.34kg (12 oz.).

TABLE OF CONTENTS
SECTION 1 - General Information
1.1 Introduction. .........................
1.2 Warranty Information .................
1.3 Manual Addenda .....................
1.4 Safety Symbols and Terms ............
1.5 Unpacking and Inspection .............
1.6 Specifications ........................
.......
.......
.......
.......
.......
.......
.: 2
3
3
3
SECTION 2 - Operation
2.1 Introduction .......................................... 5
2.2 Safety Precautions .................................... 5
2.3 Wiring ............................................... 5
2.4 Installation and Removal .............................. 6
2.5 Operating Considerations ............................. 7
2.6
Applications ......................................... 11
2.6.1 Shielded .......................................... 11
2.6.2 Guarded.. ........................................ 12
2.6.3 Driven Guard ..................................... 12
2.6.4 4-Wire ............................................. 13
SECTION 3 - Servicing Information
3.1 Introduction ......................................... 17
3.2 Handling and Cleaning .............................. 17
3.3 Recommended Test Equipment, ....................... 18
3.4 Contact Resistance Test ............................... 18
3.5 Isolation Tests ....................................... 19
3.5.1 Channel Isolation .................................. 20
3.5.2 Input Isolation., ................................... 22

SECTION 4 - Replaceable Parts
4.1
4.2
4.3
4.4
4.5
Introduction...............,,,...........,,..........
Replaceable Parts
Ordering Information 25
Factory Service .,. 25
Component Layout and Schematic Dmgram., 26
ii

LIST OF TABLES
SECTION 3 - Servicing Information
3-l Recommended Test Equipment. 18
SECTION 4 - Replaceable Parts
4-1 Model 7l54 Replaceable Parts 26
iii/iv

LIST OF ILLUSTRATIONS
SECTION 1 - General Information
l-1 Model 7l54 Simplified Schematic. 1
SECTION 2 - Operation
2-l
2-2
2-3
2-4
2-5
2-6
Limiting Capacitive Reaction Current .................
Limiting Inductive Reaction Voltage. ..................
Shielded Floating Measurement ......................
Guarded Floating Measurement. .....................
Single-Pole Switch with Switched Guard .............
Source with External Sense or Kelvin Measurement ...
9
1’10
11
12
.l3
15
SECTION 3 - Servicing Information
3-l Contact Resistance ................................... 19
3-2 Channel Isolation .................................... 21
3-3 Input Isolation ...................................... 23
SECTION 4 - Replaceable Parts
4-l Model 7154 Component Layout 27
4-2 Model 7l54 Schematic Diagram 29

SECTION 1
General Information
1.1 INTRODUCTION
The Model 7154is a 2.pole high voltage scanner card that switches signal
levels up to llOOV, 0.5A or IOVA peak (lOmA at 1OOOV)for resistive loads
only. Each of the 10channels on the card consists of a double-pole, nor-
mally open (Z-Form A) relay with a user selectable shield or driven
guard connection and a fused input. The output connection and the
input connections have screw terminals with a maximum allowable wire
size of No. 16 AWG. A schematic representation is shown in Figure 1-l.
”
CH. t I.
Figure l-l. Model 7154 Simplified Schematic
1

Switching is done in less than Zmsec exclusive of the mainframe, and
the specified contact life is >lO’ closures with cold switching and >lO*
closures at maximum signal levels. The relay drive current is 57mAirelay.
The Model i’l54 is field installable in an appropriate Keithley scanner
mainframe (e.g. Model 705 or Model 706). With the isolation between
each channel being greater than 1OYl and less than lOpF, each chan-
nel is well insulated from cross channel noise and interference.
1.2 WARRANTY INFORMATION
Warranty information is stated on the inside front cover of this manual.
If there is a need for service, contact the Keithley representative or
authorized repair facility in your area. Check the back cover for ad-
dresses. The service form supplied at the end of the manual should
be used to provide the service facility with information concerning any
difficulty.
1.3 MANUAL ADDENDA
Product improvements or changes to this manual will be explained on
an addendum included with the manual. It is recommended that this
information be incorporated immediately into the appropriate places
in the manual.
If an additional instruction manual is required, order the manual
package (Keithley Part Number 7154-901-00). The manual package in-
cludes an instruction manual and all pertinent addenda.
2

1.4 SAFETY SYMBOLS AND TERMS
The symbol A on the card denotes that the user should refer to the
operating instructions.
The symbol & denotes that a high voltage may be present on the
terminals.
The WARNING used in this manual explains danger? that could result
in personal injury or death.
The CAUTION used in this manual explains hazards that could damage
the instrument.
1.5 UNPACKING AND INSPECTION
The Model 7154was inspected both electrically and mechanically before
shipment. Upon receiving the Model 7154, unpack all items from the
shipping carton and check for any obvious damage that may have oc-
curred during transit. Report any damage to the shipping agent. Re-
tain and use the original packaging materials in case reshipment is
necessary The following items are shipped with every Model 7154:
Model 7154 Z-Pole High Voltage Scanner Card
Model 7154 Instruction Manual
1.6 SPECIFICATIONS
Detailed specifications of the Model 7154 precede the Table of Contents
of this manual.
314

SECTION 2
Operation
2.1 INTRODUCTION
This section provides information needed to use the Model 71542-Pole
High Voltage Card with the Models 705 and 706 scanner mainframes.
Once the card is installed in the mainframe, refer to the mainframe in-
struction manual for complete operating instructions.
2.2 SAFETY PRECAUTIONS
WARNING
User supplied lethal voltages may be present on the PC
board or the connections. Turn off all Dower and
discharge stored energy in external circuitry before mak-
ing or breaking connections.
1. Do not exceed the Model ?l54 maximum voltages of -tllOOV peak
terminal to terminal and +llOOV peak any terminal to chassis.
2. Make sure the scanner mainframe is grounded through an earth
grounded receptacle before operation.
3. inspect all test lead connections for wear and defects such as cracks
and exposed wires.
4. Use appropriately rated cables when switching high voltages.
2.3 WIRING
Each channel on the Model il54 card consists of a double-pole. nor-
mally open (2.Form A) switching relay. The Model 7154 will switch any
one of the 10 signals (inputs) to one output, or switch one signal to
any one of 10 outputs. See Figure 1-l.
5

NOTE
Because of the high impedance of the board, take special
care when handling and using to prevent degradation of
performance. Handle the board by the edges to avoid con-
taminating it with dirt, body oil, etc. For cleaning instruc-
tions, see paragraph 3.2.
1. Wiring is accomplished by means of terminal strips as shown on the
component layout (see Figure 4-l). Each channel has a HI connec-
tion, LO connection, and GUARD connection. Guard is common
to all channels with the jumpers (Wl-WlO) installed. The Model 7154
is shipped with all jumpers installed.
2. Resistance of the relay contacts path is less than 0.2%
3. A common guard surrounds all analog signal paths.
4. Use wires or cables that are rated for greater than 11OOV.The maxi-
mum allowable wire size is No. 16 AWG. The minimum wire size
is No. 26 AWG.
5. Route the wires through the rubber clamp pads located at the rear
of the card.
2.4 INSTALLATION AND REMOVAL
Once the card is wired, insert it card-edge first into the scanner main-
frame by aligning it with the grooves in the appropriate slot. Make sure
it is properly seated into the mainframe connector. Push the locking
tabs forward to the center of the card to lock it in.
To remove a card, first turn off the mainframe and all other equipment
connected to the card. Unfasten the locking tabs on the card by pull-
ing the tabs outward. Grasp the end of the card and carefully pull it
out of the mainframe.

2.5 OPERATING CONSIDERATIONS
Since the Model 7154 is a IO-channel card, set the scanner to the 2-p&z
mode when using the Model 7154 by itself OTwhen intermixing with
other IO-channel cards. In the 2-pole scanner mode, each scanner chan-
nel controls one channel on one IO-channel card.
The 4-p& mode of operation will be discussed in Section 2.6
Signal Levels-The maximum signal levels for the Model 7l54 2.Pole
High Voltage Card are IlOOV maximum, 0.5A or 1OVApeak for resistive
loads only. The specified contact life is >lO” closures with cold swit-
ching and >lO” closures at maximum signal levels.
WARNING
When switching signals greater than 30V RMS or 42.2V
peak take cere to prevent contact with live circuits which
could cease electrical shock resulting in injury or death.
Cables-Shielded cables should be used with the Model 7E4 card when
switching above 5OV.The shield should be connected to the circuit LO
or GUARD. This prevents excessive radiation from the cables from in-
terfering with any equipment. The cables must be rated for greater than
11OOV.
Fusible Links-The Model 7154 scanner card has a fusible link
(SQl-5420) in series with the high and low input side of each chan-
nel’s relay. A link opens when the current level on that channel becomes
excessive because of an external circuit misapplication or a relay failure.
The links protect the PC board from damage that is difficult to repair
(e.g. lifted or burned traces on the board).
A repair procedure for the links follows:
1. Clean out the PC board feedthru holes for the fusible link with a
desoldering tool.
7

Insert a jumper of No. 38 AWG magnet wire into the holes and solder
in place.
CAUTION
This wire must be taut to maintain voltage spacing.
CAUTION
When replacing the fusible links, use only No. 38 AWG
magnet wire. Use of any other wire may cause severe
damage to the PC board.
Check the same channel’s relay contacts for a short or insufficient
input isolation resistance and replace the relay if necessary. See Sec-
tions 3 and 4.
Clean the PC board according to the instructions given in paragraph
3.2.
Depending on your application, a current limiting resistor can be used
in place of a fusible link. Each resistor will limit the current flow through
one side (HI or LO) of one channel. The resistors must be of sufficient
power rating to safely dissipate any overload.
Reactive Loads-The Model 7154 is specified for resistive loads only.
Since reactive loads can cause excessive currents and voltages, current
surge limiting (for capacitive loads) and voltage clamping (for induc-
tive loads) are required to prevent damaging the relays and external
circuitry
1. Capacitive Loads - The surge current from a capacitive load must
be less than 0.5A to protect the relays. Figure 2-l shows typical cir-
cuits to limit current surges. Also, consider the maximum load of
1OVAwhen determining the current limit. For example, when switch-
ing 5OOV,the current must be limited to 20mA (I = lOVA/5OOV) and
the limiting resistor calculation of Figure 2.lA would be:
R = V/l = 500Vi20mA = 25kQ

2. Inductive Loads Inductive reaction voltage, L(di/dt), must be less
than 11OOV.Typical clamping circuits are shown in Figure 2-2. Also,
consider the maximum load of 1OVAwhen determining the voltage
limit, For example, when switching 4OmA, the voltage must be
limited to 250V (V = lOVAi40mA) and the clamping resistor calcula-
tion of Figure 2.2A would be:
R = V/l = 250Vi40mA = 62500
A. RESISTOR LIMITED
g-Jqy%y
* HIGH RESISTANCE COLD.
LOW RESISTANCE HOT.
FAST THERMAL RECOVERY.
6. THERMISTOR LIMITED
LOAD
Figure 2-1. Limiting Capacitive Reaction Current
9

f-Ji--#~j LoAD
A. RESISTOR CLAMPED (AC OR DC VOLTAGES)
H +
CD
0
LOAD
L
B. DK)DE CLAMPED (DC VOLTAGES)
!Y-Jl-jEF) LoAD
C. ZENER CLAMPED (AC VOLTAGES)
”
IN
a!-
7154
L
H c
CD
LOAD
R.
L
D. RESISTORCAPACITOR CLAMPED (AC VOLTAGES)
Figure 2-2. Limiting Inductive Reaction Voltage

2.6 APPLICATIONS
The Model 7154 can monitor high voltages from 10 different devices
under test (DUT), switch a high voltage source to 10 separate DUTs,
or connect multiple DUTs to multiple sources.
2.6.1 Shielded
CAUTION
This application is one channel at a time. Due to the
possibility of high voltage, be aura to break one connec-
tion before connecting another or the card could be
damaged.
The measurement scheme shown in Figure 2-3 is used to make a shield-
ed floating measurement on up to 10 DUTs with one meter. The guard
traces are used as a shield, so they are connected to the meter’s LO.
If both GUARD pins can not be kept at the same potential, remove the
jumper.
N : 1, Jumper in or OUIdepending on system grounding 9~heme
Figure 2-3. Shielded Floating Measurement
11