KEPCO MST-MHT Series User manual

OPERATOR’S MANUAL
IMPORTANT NOTES:
1) This manual is valid for the following Model and associated serial numbers:
MODEL SERIAL NO. REV. NO.
2) A Change Page may be included at the end of the manual. All applicable changes and
revision number changes are documented with reference to the equipment serial num-
bers. Before using this Instruction Manual, check your equipment serial number to identify
your model. If in doubt, contact your nearest Kepco Representative, or the Kepco Docu-
mentation Office in New York, [phone], requesting the correct revision for your par-
ticular model and serial number.
3) The contents of this manual are protected by copyright. Reproduction of any part can be
made only with the specific written permission of Kepco, Inc.
Data subject to change without notice.
KEPCO®
THE POWER SUPPLIER™
KEPCO INC.
An ISO 9001 Company.
KEPCO, INC. 131-38 SANFORD AVENUE FLUSHING, NY. 11355 U.S.A. TEL [phone] FAX [phone]
email: [e-mail] World Wide Web: www.kepcopower.com
MST-MHT SERIES
POWER MODULE
DIGITALLY CONTROLLED POWER MODULE SYSTEM
1/9 RACK SIZE 200 WATT POWER MODULES
FOR USE WITH KEPCO POWER MODULE CONTROLLERS
©2020, KEPCO, INC
P/N 228-1924-r1
MODELS
MST 6-20MHT, MST 15-12MHT,
MST 25-8MHT, MST 36-5MHT,
MST 55-3.5MHT, MST 75-2.5MHT,
MST 100-2MHT, MST 150-1.2MHT

228-1364 COND/CONFORM 071320 A
Conditions of Conformance
MST “Modular” products
When this product is used in applications governed by the requirements of the EEC, the following restric-
tions and conditions apply:
1. For European applications, requiring compliance to the Low Voltage Directive, 73/23/EEC, this power
supply is considered a component product, designed for “built in” applications. Because it is incom-
plete in construction, the end product enclosure must provide for compliance to any remaining electri-
cal safety requirements and act as a fire enclosure. (EN61010-1:2001 Cl. 6, Cl. 7, Cl.8, and Cl. 9)
2. This power supply is designed for stationary installation, with mains power applied via a KEPCO Rack
Adapter.
3. This power supply is considered a Class 1 (earthed) product. It is intended for use as part of equip-
ment meant for test, measurement and laboratory use, and is designed to operate from single phase,
three wire power systems. This equipment must be installed in a specifically designed KEPCO rack
adapter and within a suitably wired equipment rack, utilizing a three wire (grounded) mains connection.
See wiring section of this manual for complete electrical wiring instructions. (EN61010-1:2001
Cl.6.10.1)
4. This power supply has secondary output circuits that are considered hazardous.
5. The output wiring terminals of this power supply have not been evaluated for field wiring and, there-
fore, must be properly configured by the end product manufacturer prior to use.
6. This power supply employs a supplementary circuit protector in the form of a fuse mounted within its
enclosure. The fuse protects the power supply itself from damage in the event of a fault condition. For
complete circuit protection of the end product, as well as the building wiring, it is required that a pri-
mary circuit protection device be fitted to the branch circuit wiring. (EN61010-1:2001 Cl. 9.5)
7. Hazardous voltages are present within this power supply during normal operation. All operator adjust-
ments to the product are made via externally accessible switches, controls and signal lines as speci-
fied within the product operating instructions. There are no user or operator serviceable parts within
the product enclosure. Refer all servicing to qualified and trained Kepco service technicians.

B071320
SAFETY INSTRUCTIONS
1. Installation, Operation and Service Precautions
This product is designed for use in accordance with EN 61010-1 and UL 3101 for Installation Category 2,
Pollution Degree 2. Hazardous voltages are present within this product during normal operation. This
product is designed for use in a KEPCO Rack Adapter product. Operation of this product without a rack
adapter should never be attempted. The product should never be operated with the cover removed
unless equivalent protection of the operator from accidental contact with hazardous internal voltages is
provided.
2. Grounding
This product is a Class 1 device which utilizes protective earthing to ensure operator safety.
3. Electric Shock Hazards
This product outputs hazardous voltage and energy levels as a function of normal operation. Operators
must be trained in its use and exercise caution as well as common sense during use to prevent accidental
shock.
There are no operator serviceable parts or adjustments within the product enclosure.
Refer all servicing to trained service technician.
Source power must be removed from the product prior to performing any servicing.
This product is designed for use with nominal a-c mains voltages indicated on the
rating nameplate.
The PROTECTIVE EARTHING CONDUCTOR TERMINAL must be properly con-
nected prior to application of source power to the product (see instructions on instal-
lation herein) in order to ensure safety from electric shock.
PROTECTIVE EARTHING CONDUCTOR TERMINAL - This symbol indicates the
point on the product to which the protective earthing conductor must be attached.
EARTH (GROUND) TERMINAL - This symbol is used to indicate a point which is
connected to the PROTECTIVE EARTHING TERMINAL. The component installer/
assembler must ensure that this point is connected to the PROTECTIVE EARTH-
ING TERMINAL.
CHASSIS TERMINAL -This symbol indicates frame (chassis) connection, which is
supplied as a point of convenience for performance purposes (see instructions on
grounding herein). This is not to be confused with the protective earthing point, and
may not be used in place of it.
This symbol appears adjacent to any external terminals at which hazardous voltage
levels as high as 500V d-c may exist in the course of normal or single fault condi-
tions.
This symbol appears adjacent to any external terminals at which hazardous voltage
levels in excess of 500V d-c may exist in the course of normal or single fault condi-
tions.
!
!
!
!
!

MST-MHT SERIES 071320 i
TABLE OF CONTENTS
SECTION PAGE
SECTION 1 - INTRODUCTION
1.1 Scope of Manual ..................................................................................................................................... 1-1
1.2 Description .............................................................................................................................................. 1-1
1.3 Specifications.......................................................................................................................................... 1-2
1.4 Features.................................................................................................................................................. 1-4
1.4.1 Control/Programming......................................................................................................................... 1-4
1.4.2 Status Indicators................................................................................................................................ 1-6
1.4.3 Front Panel Meters............................................................................................................................ 1-6
1.4.4 Output Enable/Disable and Polarity Reversal.................................................................................... 1-6
1.4.5 Protection........................................................................................................................................... 1-6
1.4.6 Series Configurations ........................................................................................................................ 1-7
1.4.7 Parallel Configuration ........................................................................................................................ 1-7
1.5 Options.................................................................................................................................................... 1-7
1.6 Accessories............................................................................................................................................. 1-7
SECTION 2 - INSTALLATION
2.1 Unpacking and Inspection....................................................................................................................... 2-1
2.2 Terminations and Controls ...................................................................................................................... 2-1
2.3 A-C Input Requirement............................................................................................................................ 2-1
2.4 Cooling.................................................................................................................................................... 2-1
2.5 Installation/Removal................................................................................................................................ 2-3
2.5.1 Changing Control Bus Address (Node or Channel Number)............................................................. 2-3
2.5.2 Installation.......................................................................................................................................... 2-5
2.5.3 Removal............................................................................................................................................. 2-6
2.6 Grounding................................................................................................................................................ 2-6
2.6.1 Safety Grounding............................................................................................................................... 2-6
2.6.2 D-C (Output) Grounding .................................................................................................................... 2-6
2.7 Preliminary Check-out............................................................................................................................. 2-7
2.7.1 Required Equipment.......................................................................................................................... 2-7
2.7.2 Initial Setup........................................................................................................................................ 2-7
2.7.3 Checkout Procedure.......................................................................................................................... 2-9
2.8 Power Module to Load Interface ............................................................................................................. 2-10
2.9 Connection, General ............................................................................................................................... 2-11
2.9.1 Load Connection with Local Error Sensing........................................................................................ 2-12
2.9.2 Load Connection with Remote Error Sensing.................................................................................... 2-12
SECTION 3 - OPERATION
3.1 Introduction to Controlling the MST-MHT Power Module Output............................................................ 3-1
3.1.1 Status Flags (Error Messages).......................................................................................................... 3-1
3.1.2 Timing Requirements for a Valid Status............................................................................................ 3-1
3.2 Operating Modes..................................................................................................................................... 3-2
3.2.1 Voltage Mode..................................................................................................................................... 3-2
3.2.2 Current Mode..................................................................................................................................... 3-2
3.3 Output Polarity Reversal ......................................................................................................................... 3-2
3.4 Output Enable and Disable ..................................................................................................................... 3-4
3.5 Parallel Operation.................................................................................................................................... 3-4
3.6 Series Operation ..................................................................................................................................... 3-5
3.7 Fault Protection....................................................................................................................................... 3-5
3.7.1 Fault Recovery................................................................................................................................... 3-6
3.7.2 Fixed Overvoltage Detector............................................................................................................... 3-6
3.7.3 Overcurrent Tracking Detector .......................................................................................................... 3-6
3.7.4 Overtemperature Detectors............................................................................................................... 3-6
3.7.5 A-C Loss Detector ............................................................................................................................. 3-7
3.7.6 Open Sense/Power Wire Protection.................................................................................................. 3-7

ii MST-MHT SERIES 071320
TABLE OF CONTENTS
SECTION PAGE
3.8 Programmable Protection....................................................................................................................... 3-7
3.8.1 Programmable Overvoltage Protection............................................................................................. 3-7
3.8.2 Programmable Current Mode Protection.......................................................................................... 3-7
3.9 Calibration............................................................................................................................................... 3-8
3.9.1 Equipment Required......................................................................................................................... 3-8
3.9.2 +5 Volts Reference Adjust (R49) ...................................................................................................... 3-10
3.9.3 Output Voltage (EO) Zero Adjust (R11) ............................................................................................ 3-10
3.9.4 Current Sense Zero Adjust (R50) ..................................................................................................... 3-10
3.9.5 Output Current IOZero Adjust (R51)................................................................................................ 3-11
3.9.6 Voltage Reference Adjust (R47) ....................................................................................................... 3-11
3.9.7 Current Reference Adjust (R48) ....................................................................................................... 3-11
3.9.8 Current (IO) Full Scale Adjust (R52) ................................................................................................. 3-12

LIST OF FIGURES
FIGURE TITLE PAGE
MST-MHT SERIES 071320 iii
LIST OF TABLES
TABLE TITLE PAGE
1-1 MST Power Supply.............................................................................................................................. iv
1-1 MST-MHT Power Supply, Mechanical Outline Drawing ....................................................................... 1-5
2-1 Front and Rear Views of the MST-MHT Power Module........................................................................ 2-2
2-2 Configuration and Calibration Controls and Test Points....................................................................... 2-5
2-3 Initial Checkout Setup........................................................................................................................... 2-8
2-4 DC Output Connector Configuration for Preliminary Checkout............................................................. 2-9
2-5 Output Impedance vs. Frequency......................................................................................................... 2-11
2-6 Connector Locations and Pin Assignments.......................................................................................... 2-13
3-1 Calibration Test Set-up ......................................................................................................................... 3-10
1-1 MST-MHT Model Parameters ...............................................................................................................1-2
1-2 MST-MHT General Specifications ........................................................................................................1-2
1-3 Accessories ...........................................................................................................................................1-7
2-1 Functions of Internal Controls ...............................................................................................................2-1
2-2 Front Panel Controls and Indicators .....................................................................................................2-2
2-3 Rear Terminations ................................................................................................................................2-3
2-4 Secondary Address Selection ...............................................................................................................2-4
2-5 DC Output Connector/Adapter Kit Terminal Designations ....................................................................2-11
3-1 Error Messages .....................................................................................................................................3-1
3-2 Maximum External Capacitance Values to Ensure Dry Switching ........................................................3-4

iv MST SERIES 071320
FIGURE 1-1. MST POWER SUPPLY

MST-MHT SERIES 071320 1-1
SECTION 1 - INTRODUCTION
1.1 SCOPE OF MANUAL
This manual contains instructions for the installation, operation, and maintenance of the MST-
MHT series of 200 Watt, voltage and current stabilized d-c programmable power supplies
(power modules) manufactured by Kepco, Inc., Flushing, New York, U.S.A. when controlled by a
Kepco Model MST 488-27HT Controller.
Details regarding the MST 488-27HT Controller can be found in the MST 488-27HT Controller
Operator Manual which is available for download from the Kepco website at:
www.kepcopower.com/support/opmanls.htm#mst
Details regarding the RA 55 Connector Adapter can be found in the Kit 219-0618 RA 55 Con-
nector Adapter Kit Instruction Sheet which is available for download from the Kepco website at:
www.kepcopower.com/support/opmanls.htm#kit
1.2 DESCRIPTION
The Kepco MST-MHT 200 Watt Series (Figure 1-1) consists of eight, single-output models as
shown in Table 1-1. MST-MHT Series Power Modules are designed to provide a functional drop-
in replacement for Keysight/Agilent/HP Series 66000A© power modules. These models also
include the following additional features: autoranging a-c input, PFC to meet IEC/EN require-
ments, current share, hot swap, built-in polarity reversal, constant current mode and greater
power (180W to 200W).
MST-MHT power modules employ a switch mode preregulator for high efficiency and power
density, with linear output stabilization for accuracy and resolution. Their modular, plug-in design
with 7" x 1-3/4” cross-section allows nine independently controlled modules to be mounted
abreast in a standard (19" x 7" x 20.9") Kepco Model RA 55H rack adapter or 5 modules in a
standard (9.6” x 7” x 20.9”) Kepco Model CA 400H case.
Each Power Module is controlled digitally via the IEEE 1118 2-wire serial bus (“Bitbus”) with 12
bits of resolution over the entire voltage and current ranges. Voltage and current are displayed
on LED panel meters, and read back over the control bus with an accuracy of 0.06%. Operating
status is displayed on front panel LED indicators and read back over the bus.
An MST-MHT Power Module can be removed and installed without powering down the system if
the module POWER switch is set to OFF. Employing current-sharing for parallel operation, they
may be “hot-swapped” for redundant (N+1) applications. MST-MHT Power Supplies can be
operated with universal a-c input power sources (90-264Vac, 47-63Hz) and incorporate power
factor correction (0.98) to meet EN 61000-3-2. MST-MHT Power Modules can also be config-
ured in series for higher than rated output voltages (500V d-c maximum)

1-2 MST-MHT SERIES 071320
.
1.3 SPECIFICATIONS
The MST-MHT Series electrical and mechanical specifications are listed in Tables 1-1 and 1-2.
TABLE 1-1. MST-MHT MODEL PARAMETERS
MODEL
OUTPUT
VOLTAGE
Adjustment
Range
(V d-c)
OVERVOLTAGE
(V d-c) OUTPUT CURRENT Maximum (Amps) RIPPLE/NOISE EFFICIENCY
(100% Load
120V a-c)
Programmable
(max.)
Hardware
Trigger
(See Note) 45°C 55°C 65°C mVrms mVp-p
MST 6-20MHT 0-6 7.2 7.4 20 16 12 2 5 51%
MST 15-12MHT 0-15 18 18.3 12 9.6 7.2 3 7 61%
MST 25-8MHT 0-25 30 30.6 8 6.4 4.8 4 8 62%
MST 36-5MHT 0-36 42 42.8 5 4.0 3.0 5 10 63%
MST 55-3.5MHT 0-55 66 67.3 3.5 2.8 2.1 9 15 64%
MST 75.2.5MHT 0-75 90 91.8 2.5 2.0 1.5 12 20 64%
MST 100-2MHT 0-100 120 122.4 2.0 1.6 1.2 15 35 66%
MST 150-1.2MHT 0-150 180 183.6 1.2 1.0 0.7 20 45 66%
NOTE: Minimum 2% above Programmable (max.),
TABLE 1-2. MST-MHT GENERAL SPECIFICATIONS
SPECIFICATIONS RATING/DESCRIPTION CONDITION
INPUT
A-C Voltage nominal 100-250V a-c Single phase
range 90-264 Va-c Brownout Voltage 85Vrms
Frequency nominal 50-60 Hz At >63 Hz, input leakage current
exceeds specifications
range 47 – 63 Hz (400 Hz)
Input Current maximum 3.6A rms 90V a-c Input
Current Harmonics Within EN 61000-3-2 limits Any source condition, rated load
Efficiency minimum See Model Table 1-1 120V a-c, rated output Load
EMI FCC Class A, CISPR 11 Class A Conducted Emissions
Leakage Current
120V a-c,
60Hz <0.5 mA
240V a-c,
50Hz <1.0 mA
Power Factor 0.98 min. All source conditions, full load
EMC Complies with IEC 61326-1, Class A
OUTPUT
Source Effect Voltage 0.001% 90 – 132, 176 – 264V a-c,
any load condition
Current 0.005%
Load Effect Voltage ±0.002% or 1mV, whichever is greater 10% to 100% Load at EMAX,
any source condition
Current ±0.005% 10% to 100% Load at IMAX
Temperature Effect Voltage 0.01%/°C Any source/load condition
(0 – 45° C)
Current 0.02%/°C

MST-MHT SERIES 071320 1-3
Time Effect (drift) Voltage 0.01% 0.5 – 8.5 hours
Any source/load condition
Current 0.02%
Programming
Resolution Voltage 12 Bits, 0.024% % of EMAX
Current 12 Bits, 0.024% % of IMAX
Data Read Back
Accuracy Voltage 0.1% % of EMAX
Current 0.12% % of IMAX
Transient Recovery Time 100 Microseconds
(500 Microseconds for MST 6-20MHT) Return to within stabilization band from 50% load step
Turn On/Off Overshoot None Any source/load condition
Error Sense 0.5V maximum/wire Any source/load condition
MISCELLANEOUS
Temperature 0° to +65° C,start from –20°C (see Table 1-1) Operating
–40° to +85° C Storage
Humidity 0 to 95% RH Non-condensing Operating &
Storage
Shock 20G 11 msec ±50% half sine 3 axes, 3 shocks each axis,
non-operating
Vibration 5 – 10Hz 10mm double amplitude Non-operating, 1 hour each axis
10 – 55 Hz 2G
Altitude Sea level to 10,000 ft. Any source/load condition
Isolation (Output – Case) ±500 V d-c
Display Voltage 3.5 Digit LED, red Front panel,
For reference only
Current 3.5 Digit LED, red
Status Indicators Voltage Mode Green LED
Current Mode Amber LED
Current Share Amber LED
Output Enabled Green LED
Polarity Reversed Green LED
Output Fault Red LED
Output Enable Built in power and sense relay
Polarity Reversal Built in power and sense relay
Parallel Connection N+1 redundancy, forced current share Currents divided equally
Overvoltage protection (OVP) Programmable: Up to 120% of nominal voltage See Par. 3.7.3
Hardware Trigger: Tracks output setting, power shutdown if OVP > 120% of
nominal voltage See Par. 3.7.2
Overcurrent Protection (OCP) Tracks output current. Shutdown selectable upon either
exceeding rated current by 10% or immediate See Par. 3.7.3
Overtemperature Thermostat See PAR. 3.7.4
Open sense wire Automatic detection with power shutdown See PAR. 3.7.6
Backup current limit Tracks output current at 110%
TABLE 1-2. MST-MHT GENERAL SPECIFICATIONS (CONTINUED)
SPECIFICATIONS RATING/DESCRIPTION CONDITION

1-4 MST-MHT SERIES 071320
1.4 FEATURES
1.4.1 CONTROL/PROGRAMMING
Control of the MST-MHT Power Module is via the IEEE 1118 2-wire serial bus operating at
375KHz; as many as 27 separate modules of the MST-MHT Series can be addressed via the
bus. Decoders for RS232, IEEE-488 and VXI are available in modular form and stand-alone
types. Controller Model MST 488-27HT plugs into a slot in a Model RA 55H Rack Adapter and
allows host computers designed for RS232 or IEEE 488 bus communication to control the MST-
MHT via the IEEE 1118 bus compatible with Keysight/Agilent/HP 66000© Series.
PHYSICAL
Type of Construction Enclosed, plug-in style includes status LEDs, two digital
meters, handle and ON/OFF switch
Cooling Internal D-C Cooling Fans Exhaust to rear
Module
Dimensions English 7” x 1.83” x 20” Refer to Figure 1-1
Metric 178 x 46.5 x 508 mm
Weight English 8 lbs.
Metric 3.6 Kg.
Load Connection Mates with Positronic POW-R-LOK Series 6 pin connec- tor, Kepco P/N 143-0458 (See Figure 2-6 and Table 2-5), Mating connectors provided with MST-MHT compatible rack
adapters
Source Connection Mates with Molex Minifit, Jr. Series 10 pin connector, Kepco p/n 143-0544 (See Figure 2-6) Mates with a-c backplane in MST-MHT compatible rack
adapters
TABLE 1-2. MST-MHT GENERAL SPECIFICATIONS (CONTINUED)
SPECIFICATIONS RATING/DESCRIPTION CONDITION

MST-MHT SERIES 071320 1-5
FIGURE 1-1. MST-MHT POWER SUPPLY, MECHANICAL OUTLINE DRAWING

1-6 MST-MHT SERIES 071320
1.4.2 STATUS INDICATORS
Six status indicators at the front panel provide operational information (see Table 2-2):
• VOLTAGE MODE
• CURRENT MODE
• CURRENT SHARE
• OUTPUT ENABLED
• POLARITY REVERSED
•OUTPUTFAULT
1.4.3 FRONT PANEL METERS
Two digital meters at the front panel provide displays of output voltage and current. These dis-
plays show 3.5 digits and are provided for reference only, accurate to 0.5% (typical) for voltage
and 1.5% (typical) for current.
1.4.4 OUTPUT ENABLE/DISABLE AND POLARITY REVERSAL
The MST-MHT Power Module features integral relays to enable/disable the output. Separate
relays are provided for power and sense connections. Disabling the MST-MHT as a voltage
source means opening the connection between the power supply and its load. Disabling the
MST-MHT as a current source means shorting the power supply's output terminals. Polarity
reversal relays are installed, but not supported at this time. If polarity reversal is needed, refer to
Kepco’s MST Series.
1.4.5 PROTECTION
The MST-MHT Power Module incorporates the following protection circuits which cause the
MST-MHT to automatically isolate the load and force power module output voltage and current
to zero.
• Overvoltage protection: Automatic (non-adjustable) power shutdown if the output
exceeds hardware trigger value specified in Table 1-1.
• Overcurrent protection: Programmable, tracks output current; disables output if output
current exceeds programmed value (see PAR. 3.7.2).
• Overtemperature: Activated when the internal temperature exceeds a safe operating
threshold (see PAR. 3.7.4).
• AC loss: Activated if loss of source power detected (see PAR. 3.7.5).
• Open power lead and sense wire: Activated if an open sense wire or open power lead is
detected (see PAR. 3.7.6).

MST-MHT SERIES 071320 1-7/(1-8 Blank)
1.4.6 SERIES CONFIGURATIONS
The output of the MST-MHT Power Module “floats;” so that MST-MHT Power Modules can be
connected in series to obtain higher output voltages, up to a maximum of ± 500 Volts d-c (±400
Volts d-c when Adapter KIT 219-0618 is installed on the OUTPUT connector at the rack
adapter) referenced to the chassis (see PAR. 3.6).
1.4.7 PARALLEL CONFIGURATION
A parallel configuration may be employed for higher output current and for N + 1 redundant,
“hot-swap” applications. When connected in a parallel configuration, MST-MHT Power Modules
employ forced current sharing to ensure equal distribution of the load among all power modules,
improving performance, reducing component stress, and increasing reliability (see PAR. 3.5).
1.5 OPTIONS
The HT option (HT appended to the Model Number, e.g., MST 6-20MHT) incorporates addi-
tional filtering to provide significant output noise reduction in the range of 1KHz to 10MHz, com-
patible with Keysight/Agilent/HP 66000© mainframe. Contact Kepco Sales Engineering for
additional information regarding performance and availability of other options such as output
current monitoring where a 0 to 2V signal corresponds to 0 to INOM.
1.6 ACCESSORIES
The MST-MHT Power Module is designed for installation in Kepco Rack Adapter Model RA 55H
which accommodates nine 1/9 rack size power modules. With a 1/9 rack Controller module
installed, the RA 55H will accommodate eight 1/9 rack power modules. Connecting cables and
IEEE 1118 bus daisy chain terminations are supplied with the RA 55H Rack Adapter. Additional
accessories are listed in Table 1-3.
TABLE 1-3. ACCESSORIES
ACCESSORY PART NUMBER USE
OUTPUT LOAD CONNECTOR
ADAPTER (supplied with RA
55H Rack Adapter)
KIT 219-0618 Allows output load connections of up to 20 Amperes to MST-MHT
power module not installed in RA 55H Rack Adapter (for advanced
troubleshooting). Adapter is terminated at one end with mating con-
nector for MST-MHT module output connector. The opposite end is
terminated with 6 terminals having crimp-ready ring lugs used for out-
put power, sensing, ground and load sharing connections. This
adapter is typically used in conjunction with 118-0850 Input Power/
Communication Cable.
INPUT POWER/COMMUNICA-
TION CABLE (Used for stand-
alone module Communication/
calibration)
118-0850 Allows power and communication connections to MST-MHT power
module not installed in RA 55H Rack Adapter (for advanced trouble-
shooting). Cable length is approximately 7 feet, terminated at one end
with mating connector for MST-MHT module a-c input/control bus con-
nector. The opposite end of the cable is split into two terminations, one
a NEMA 5-20P a-c mains plug and the other a 9-pin D-sub connector
that mates with the control bus connector of RA 55H (as well as CA
400H and MST 488-27HT). This cable is typically used in conjunction
with Kit 219-0618 Output Load Connector Adapter.
MATING CONNECTOR
(DC OUTPUT) (Used for Calibra-
tion) 142-0372 Mates with DC OUTPUT connector, Kepco P/N 143-0457 (Positronic
POW-R-LOK Series 6 pin connector). This item is typically used in
conjunction with 118-0850 Input Power/Communication Cable.
LOAD CONNECTOR PINS
(Used for Calibration) 107-0327 Replacement pins for DC OUTPUT connector. This item is typically
used in conjunction with 118-0850 Input Power/Communication Cable.

MST-MHT SERIES 071320 2-1
SECTION 2 - INSTALLATION
2.1 UNPACKING AND INSPECTION
This instrument has been thoroughly inspected and tested prior to packing and is ready for
operation. After careful unpacking, inspect for shipping damage before attempting to operate.
Perform the preliminary operational check as outlined in PAR. 2.7. If any indication of damage is
found, file an immediate claim with the responsible transport service.
NOTE
If the Power Modules are shipped pre-installed in the RA 55H Rack Adapter, each
module is secured to the RA 55H Rack Adapter by two shipping screws. These
screws must be removed from the bottom of the rack adapter, otherwise the mod-
ules cannot be removed from the rack adapter.
2.2 TERMINATIONS AND CONTROLS
a. Internal Calibration Controls: Refer to Figure 2-2 and Table 2-1.
b. Front Panel: Refer to Figure 2-1 and Table 2-2.
c. Rear Panel: Refer to Figure 2-1 and Table 2-3.
2.3 A-C INPUT REQUIREMENT
MST-MHT Power Modules operate from single-phase a-c mains power over the specified volt-
age and frequency ranges without adjustment or modification.
2.4 COOLING
The power transistors and rectifiers in the MST-MHT Power Module are maintained within their
operating temperature range by means of internal heat sink assemblies cooled by internal fans.
PANEL OPENINGS AND THE TOP OF THE CASE MUST BE KEPT CLEAR FROM
OBSTRUCTIONS TO INSURE PROPER AIR CIRCULATION. Maximum ambient temperature
for installed MST-MHT modules is 45°C. See technical manuals for RA 55H or CA 400H rack
TABLE 2-1. FUNCTIONS OF INTERNAL CONTROLS
REFERENCE
DESIGNATION CONTROL PURPOSE
R49 +5 V REF This is a primary adjustment for the analog circuits.
R11 EOZero This control is used to adjust the output voltage of the Power Module to
zero. EO Zero calibrates the Power Module in the Voltage mode.
R51 IO Zero This control is used to adjust the output current of the Power Module to
zero. IO Zero calibrates the Power Module in the Current mode.
R50 Current Sensing Zero This adjustment calibrates the current monitor amplifier to zero.
R52 Full Scale Current Adjust This adjustment calibrates the programmed full scale value.
R47 VREF This is a full scale voltage adjustment.
R48 IREF This is a current read back accuracy adjustment.

2-2 MST-MHT SERIES 071320
adapters for detailed cooling requirements. Periodic cleaning of the power module interior is rec-
ommended.
FIGURE 2-1. FRONT AND REAR VIEWS OF THE MST-MHT POWER MODULE
TABLE 2-2. FRONT PANEL CONTROLS AND INDICATORS
CONTROL/INDICATOR FUNCTION
POWER switch Turns a-c power ON/OFF. CAUTION: DO NOT repeatedly toggle the POWER
On/Off switch as this may cause unit to fault.
VOLTAGE MODE indicator - green LED Goes on to indicate MST-MHT is operating as a voltage source (see PAR.
3.2.1).
CURRENT MODE indicator -amber LED Goes on to indicate MST-MHT is operating as a current source (see PAR.
3.2.2).
POLARITY REVERSED indicator - green LED Goes on when negative output programmed while the output is enabled (see
PAR. 3.3).
OUTPUT ENABLE indicator - green LED Goes on to indicate power relays are closed and output regulator is enabled
(see PAR. 3.4).
OUTPUT FAULT indicator - red LED Goes on to indicate internal power module fault detected (see PAR. 3.7).
CURRENT SHARE indicator - amber LED Goes on to indicate that unit is operating as “slave” module when used in a
parallel configuration (see PAR. 3.5).
VOLTS meter Displays output voltage.
AMPS meter Displays output current.

MST-MHT SERIES 071320 2-3
2.5 INSTALLATION/REMOVAL
The MST-MHT Power Module is designed to be rack-mounted in an RA 55H Rack Adapter.
Refer to Figure 1-1 for outline dimensions. For installation in confined spaces, care must be
taken that the surrounding environment does not exceed the maximum specified ambient tem-
perature (45° C); see PAR. 2.4. The MST-MHT Power Module may be shipped either individu-
ally, or already installed in an RA 55H Rack Adapter. Follow power module installation
procedures in RA 55H Instruction Manual.
2.5.1 CHANGING CONTROL BUS ADDRESS (NODE OR CHANNEL NUMBER)
Each MST-MHT Power Module connected to the IEEE 1118 bus must have a unique address
(also referred to as node or channel number). For MST-MHT modules, this address is a second-
ary address. The primary address is reserved for the MST 488-27 Controller which then
addresses the MST-MHT modules on the bus using the secondary address. The secondary
address from 0 to 30 is selected by DIP selector switch S1 accessed through the top of the unit
(see Figure 2-2) and can be changed in accordance with Table 2-4. This address is set at Kepco
to 1.
NOTES: 1. Although 31 unique addresses are provided, the maximum number of instruments
which can be managed by the Kepco Controller is 27.
: 2, Secondary address 0 is not supported if the MST488-27HT controller is com-
manded to operate as an MST 488-27 (non-HT suffix) unit by sending SYST:SET
SA0. For this case the secondary address switch value becomes the node (pri-
mary) address of the MST power module. See the MST 488-27 (non-HT suffix)
Programmer manual for more details on this non-standard mode of operation.
TABLE 2-3. REAR TERMINATIONS
REAR TERMINATION FUNCTION
AC Input/Control Bus connector Connects the MST-MHT Power Module to single-phase a-c power, safety ground, and
two-wire IEEE 1118 bi-directional Control Bus.
DC output connector (mates with Con-
nector Adapter Kit 219-0618, installed
on either MST-MHT power module or
RA 55-H rack adapter.
Connects the MST-MHT Power Module output lines, sensing lines, frame ground lines
and current share bus to the load via Kit 219-0618 Connector Adapter. Kit 219-0618
provides enhanced filtering of the output and 6-32 screws for lug wiring.

2-4 MST-MHT SERIES 071320
TABLE 2-4. SECONDARY ADDRESS SELECTION
DECIMAL
ADDRESS
SELECTOR SWITCH S1 SECTION
(SIGNAL LINE)
A4 A3 A2 A1 A0
011111
100001
200010
300011
400100
500101
600110
700111
801000
901001
1001010
1101011
1201100
1301101
1401110
1501111
1610000
1710001
1810010
1910011
2010100
2110101
2210110
2310111
2411000
2511001
2611010
2711011
NOTE:
1. See PAR. 2.5.1for details regarding the use of secondary addressing
2. If the Power Module is already installed in a Rack Adapter and it is necessary to change
the secondary bus address, the Power Module must first be removed from the Rack
Adapter as described in PAR.2.5.3 below.