PACSystems RX3i User manual

User Manual
GFK-2749A
Jan 2020
PACSystemsTM RX3i
POWER SYNC AND MEASUREMENT SYSTEM
USER MANUAL

User Manual Contents
GFK-2749A Jan 2020
Contents i
Contents
Chapter 1: PSM Module Description and Specifications...........1
1.1 PSM System Features........................................................................................... 1
1.2 PSM Module ........................................................................................................ 2
1.3 Terminal Assembly .............................................................................................. 3
1.4 Connectors.......................................................................................................... 3
1.5 User-Supplied Equipment .................................................................................... 4
1.6 PSM Part Numbers............................................................................................... 4
1.7 Specifications ...................................................................................................... 5
1.8 System Operation................................................................................................ 7
1.8.1 Autonomous Operation ............................................................................ 8
1.8.2 Frequency Measurement........................................................................... 8
1.9 ANSI Functions Supported ................................................................................... 9
1.9.1 ANSI Functions for GRID 1 (Public Grid/Load) Protection............................ 9
Chapter 2: Installation ..........................................................18
2.1 General Warnings/Cautions............................................................................... 18
2.2 Enclosures ......................................................................................................... 19
2.3 Installing the PSM Module ................................................................................. 19
2.4 Installing the Terminal Assembly ....................................................................... 19
2.5 Connector and Cabling Information................................................................... 20
2.5.1 Basic PSM System Connections ............................................................... 20
2.5.2 Overview of PSM System Connection to Public Grid and Generator.......... 21
2.5.3 Power System Connections ..................................................................... 21
2.5.4 Relay Connector for Sync Contacts .......................................................... 24
2.6 Wiring ............................................................................................................... 25
2.6.1 General Wiring Notes .............................................................................. 25
2.6.2 Terminal Assembly Frame Ground Connection ........................................ 26
2.6.3 Wiring Diagrams ..................................................................................... 26
2.7 Scaling for PT and CT Ratios ............................................................................... 32
2.7.1 Example: ................................................................................................. 32
Chapter 3: Configuration and Data Transfer ..........................33
3.1 Configuration Parameters ................................................................................. 33
3.1.1 PSM001 Settings Parameters .................................................................. 33
3.1.2 Grid1 and Grid2 Parameters .................................................................... 34

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Contents ii
3.1.3 ANSI Protection Parameters .................................................................... 37
3.1.4 Power Consumption................................................................................ 41
3.1.5 Terminals ................................................................................................ 41
3.2 Data Transfer..................................................................................................... 41
3.2.1 PSM Status Flags ..................................................................................... 41
3.2.2 Mode Control Bits Sent to PSM module ................................................... 50
3.2.3 Parameters sent to PSM Module .............................................................. 54
3.3 Example Configurations..................................................................................... 57
3.3.1 Configuration for 120/240 VAC Single Phase System............................... 57
3.3.2 Configuration for 600VAC Single Phase System....................................... 60
3.3.3 Configuration for 120/208 WYE Three-Phase Four-Wire System .............. 62
3.3.4 Configuration for 120/208 3-Wire Delta system with Two PTs (Two Wattmeter
Method), B-Common .............................................................................. 64
3.3.5 Configuration for 120/208 3-Wire Delta system with Two PTs (Two Wattmeter
Method), C-Common .............................................................................. 66
3.3.6 Configuration for 120/208 4-Wire WYE Synchro/Power Control Connection69
3.3.7 Configuration for 480V 4-Wire WYE Synchro/Power Control Connection . 71
3.3.8 Configuration for 480V 4-Wire WYE Synchro/Power Control Connection. 74
Chapter 4: Diagnostics..........................................................78
4.1 PSM Module LED Indicators ............................................................................... 78
4.2 PSM Module Health Status................................................................................. 78
4.3 Point Faults........................................................................................................ 78
4.3.1 Point Fault Configuration ........................................................................ 79
4.3.2 Fault and No-Fault Contacts .................................................................... 79
Appendix A: Product Certifications and Installation Guidelines for
Conformance............................................................................80
A.1 Agency Approvals.............................................................................................. 80
A.2 Environmental Specifications............................................................................. 81
A.3 Government Regulations................................................................................... 82

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iii
Warnings, Caution Notes as Used in this Publication
Warning
Warning notices are used in this publication to emphasize that hazardous voltages,
currents, temperatures, or other conditions that could cause personal injury to exist
in this equipment or may be associated with its use.
In situations where inattention could cause either personal injury or damage to
equipment, a Warning notice is used.
Caution
Caution notices are used where equipment might be damaged if care is not taken.
Notes: Notes merely call attention to information that is especially significant to understanding and operating
the equipment.
These instructions do not purport to cover all details or variations in equipment, nor to provide for every
possible contingency to be met during installation, operation, and maintenance. The information is supplied
for informational purposes only, and Emerson makes no warranty as to the accuracy of the information
included herein. Changes, modifications, and/or improvements to equipment and specifications are made
periodically and these changes may or may not be reflected herein. It is understood that Emerson may make
changes, modifications, or improvements to the equipment referenced herein or to the document itself at any
time. This document is intended for trained personnel familiar with the Emerson products referenced herein.
Emerson may have patents or pending patent applications covering subject matter in this document. The
furnishing of this document does not provide any license whatsoever to any of these patents.
Emerson provides the following document and the information included therein as-is and without warranty of
any kind, expressed or implied, including but not limited to any implied statutory warranty of merchantability
or fitness for particular purpose.

User Manual Chapter 1
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PSM Module Description and Specifications 1
Chapter 1: PSM Module Description and
Specifications
The Power Sync and Measurement (PSM) system monitors two independent three-phase
power grids. It incorporates advanced digital signal processor (DSP) technology to
continuously process three voltage inputs and four current inputs for each grid.
Measurements include RMS voltages, RMS currents, RMS power, frequency, and phase
relationship between the phase voltages of both grids.
The PSM module performs calculations on each captured waveform, with the DSP
processing the data in less than two-thirds of a power line cycle. The PSM module can be
used with wye or delta type three-phase power systems or with single-phase power
systems.
The PSM system can be used for applications such as:
•Electrical power consumption monitoring and reporting
•Fault monitoring
•Generator control features for generator to power grid synchronization
•Demand penalty cost reduction/load shedding
The PSM system consists of:
•PSM module –A standard IC694 module that mounts in an RX3i main rack. The PSM
module provides the DSP capability.
•Terminal Assembly –A panel-mounted unit that provides the interface between the
PSM module and the input transformers.
•Interface cables –Provide the GRID 1 and GRID 2 connections between the PSM module
and the Terminal Assembly.
1.1 PSM System Features
•Uses standard, user-supplied current transformers (CTs) and potential transformers
(PTs) as its input devices.
•Accurately measures RMS voltage and current, power, power factor, frequency, energy,
and total, three-phase, 15-minute power demand.
•Provides two isolated relays that close when the voltage phase relationships between
the two monitored grids are within the specified ANSI 25 limits provided by the RX3i
host controller. These contacts can be used for general-purpose, lamp duty or pilot duty
loads. Voltage and current ratings for these load types are provided on page 5.
•Provides a cable monitoring function that indicates when the cables linking the PSM
module and Terminal Assembly are correctly installed.
•Can be easily calibrated using the PACTM Machine Edition software to enter calibration
constants for the PSM module and Terminal Assembly.

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PSM Module Description and Specifications 2
•The PSM001 module supports hot swap (removal and replacement in an RX3i rack
that is under power).
1.2 PSM Module
In addition to configuring the PSM module upon project download from PME, the RX3i CPU
can control the PSM module by updating configuration data from the RX3i in the form of
%AQ data words and %Q mode control bits during each sweep.
The PSM module provides calculated data to the CPU in the form of %AI data words and %I
status bits each sweep. The information sent by the PSM module includes power system
measurements and discrete fault status.
Connectors
The PSM module provides two Mini-D 20-pin connectors that accept the GRID 1 and GRID 2
voltage and current signals from the Terminal Assembly.
Indicators
Four LEDs provide status indications for the PSM system.
Figure 1

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PSM Module Description and Specifications 3
RUN
Green
The module is operating correctly and communicating with the
RX3i.
Red
The module is operating without backplane communication.
Off
The module is not operating.
FLT
Green,
blinking
During the period when GREEN is ON, Grid 2 can be connected to
Grid 1.
Green,
steady
Grid 1 and Grid 2 can be connected and there are no faults.
Red
The module has detected a fault condition.
Off
The module has not detected a fault and the grids are not
synchronized.
GRID 1
Green
Indicates a voltage signal has been detected on Grid 1.
Red
A frequency out-of-range condition has been detected on Grid 1.
Off
No zero-crossing signal of Grid 1 has been detected during the
last 250 ms time period.
GRID 2
Green
Indicates a voltage signal has been detected on Grid 2
Red
A frequency out-of-range condition has been detected on Grid 2.
Off
No zero-crossing signal of Grid 2 has been detected during the
last 250 ms time period.
1.3 Terminal Assembly
The Terminal Assembly accepts three voltage inputs and four current inputs for each of two
grids. The Terminal Assembly translates the 0–5 A current signals and the 45–690 VAC RMS
voltage signals to low voltage signals for use by the PSM module.
Voltage inputs are connected through external, user-supplied potential transformers (PT).
External, appropriately-sized current transformers (CT) are used to translate grid or load
currents down to the 0–5 A range required by the Terminal Assembly.
1.4 Connectors
The Terminal Assembly provides two terminal blocks, each with 12 screw terminals, for the
voltage and current inputs from the grids. The terminals accept up to 10 AWG wire
commonly used in power utility applications.
The Terminal Assembly provides two pairs of Mini-D 20-pin connectors for connection to
the PSM module using the interface cables. The 45–120 VAC or 120–690 VAC range is
selected by connecting the interface cables to the corresponding pair of Mini-D connectors.
When the cables are connected to the correct grid and matching voltage ranges, the PSM
module provides an indication that the cables are correctly attached to the unit.

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PSM Module Description and Specifications 4
A four-pin pluggable connector provides two isolated solid-state relay contacts that close
when the correct voltage, phase, and relative frequency differences match the configured
criteria for synchronization of the GRID1 and GRID2 signals
Note: The Terminal Assembly is not equipped with CT shorting-bars. These must be provided
separately by the user.
Figure 2
1.5 User-Supplied Equipment
The user must supply the following components depending upon the application. This
equipment includes:
•Current transformers, 5 Amps
•Potential transformers
•Fuses (1 Amp each) for each voltage lead connected to the Terminal Assembly.
•A fuse (1 Amp) for the common or return line for the voltage lead on the Terminal
Assembly.
•A CT shorting block for each current transformer (CT) connection used on the Terminal
Assembly when used with external CTs.
1.6 PSM Part Numbers
Part Number
Description
IC694PSK001
PSM System. Includes a PSM module, a Terminal Assembly and two interface
cables
IC694PSM001
Replacement PSM module
IC694ACC200
Replacement Terminal Assembly

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PSM Module Description and Specifications 5
Part Number
Description
IC694CBL200
One replacement 2m (6.56 ft.) interface cable
IC694ACC201
PSM replacement parts:
two finger guards
four thumb screws
one relay connector
two grounding lug nuts
1.7 Specifications
PSM Module Power Requirements
Backplane Power Consumption
400 mA max. at 5 VDC
Total Power Dissipation
2.0 W max.
Isolation from Backplane
1500 VDC
Host Controller Compatibility
RX3i CPUs
For specific versions supported, refer to “Functional
Compatibility” in the Important Product Information
document, GFK-2748.
Maximum number of PSM modules per
RX3i system
No restrictions, as long as the power supply has sufficient
capacity
Sync Relay contacts
Two isolated relay outputs
General purpose:
125 VAC / 125 VDC maximum at 1 amp
Lamp duty:
125 VAC / 125 VDC maximum at 1 amp
Pilot duty:
125 VAC / 125 VDC maximum at 0.35 amp
Switching speeds
20ms
5ms
Turn-on time
Turn-off time
Measurement Specifications
Three voltage inputs per grid
All voltage data is scaled in 0.1 VAC units.
Impedance
>1 MΩ
Range
Low range
High range
45–150 VAC RMS (120VAC nominal)
120–690 VAC RMS (600VAC CAT IV; 690 VAC CAT III)
Frequency
40–70 Hz
Four current inputs per grid
All current data is scaled in 0.001 Amp units.
Impedance
<5 milliohms
Range
0–5 A RMS (5 A nominal)

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PSM Module Description and Specifications 6
Frequency
40–70 Hz
Phase difference between grids:
±180O
Measurement Accuracy 1
Voltage
0.2% of Full Scale (see page 52)
Current
0.2% of Full Scale (see page 51)
kW, kVAR, kVA
0.4%
kWH, kVARH, kVAH
0.4%
Power factor
1%
Frequency
0.01 Hz
Phase angle
0.1O
Terminal Assembly Input Terminal Ratings
Current
15 Amps continuous maximum
Voltage
690 VAC RMS
Sync Relay contacts
150 VAC/VDC at 1 Amp Resistive, maximum
Note: Actual contact ratings depend on load
type. See “Sync Relay contacts” on page 5.
RX3i CPU Memory Requirement for Automatic Data Exchange
%I
80 bits
%Q
32 bits
%AI
64 words
%AQ
2 words
Data Exchange Time Between RX3i CPU and PSM
A complete data exchange between the PSM and RX3i occurs during each controller scan.
Minimum scan time is 3.5ms per PSM module in the backplane. Minimum data update rate is one
power line period. See “System Operation” on page 7 and “PSM Status Flags” in Chapter 3:.
ANSI Protective Functions
ANSI 25 –Generator and Public Grid Synchronization
ANSI 27 –Under-voltage Protection
ANSI 32 –Reverse Power Protection
ANSI 47 –Voltage Phase Sequence Protection
ANSI 50 –Instantaneous Over-current Protection
ANSI 59 –Over-voltage Protection
ANSI 60 –Voltage (Current) Imbalance Protection
ANSI 81U –Under-frequency Protection
ANSI 81O –Over-frequency Protection

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PSM Module Description and Specifications 7
Power Measurement Configurations
Four-wire three phase wye systems: 3 PTs and 3 CTs plus Neutral CT (optional)
Three-wire three phase delta systems: 2 PTs and 2 CTs
Three independent single phase systems: 1 PT and 1 CT for each phase
Three-wire single phase systems: 120/240 (2 PTs and 2 CTs)
Operating Environment
Enclosure mounting
Required. PSM module and Terminal Assembly must be
installed in a NEMA/UL Type 1 enclosure or an IP20
rating providing at least a pollution degree 2
environment.
When this system is installed in an area designated as
Class 1 Zone 2 in Europe, compliance with the ATEX
Directive requires an enclosure with a minimum rating
of IP54.
1.8 System Operation
The PSM digitizes the voltage and current input waveforms from Grid 1 and Grid 2, storing
the results into internal memory buffers. Data is updated every power line cycle.
Therefore, the data is updated every 20ms on a 50Hz power grid, or every 16.67ms on a
60Hz power grid.
While background processes analyze a set of waveforms stored in one memory buffer, the
next set of waveforms is captured and stored in another buffer. In this way, calculations are
performed on each waveform with the DSP processing the data in about two-thirds of a
power line cycle.
Figure 3

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PSM Module Description and Specifications 8
1.8.1 Autonomous Operation
The PSM is a semi-autonomous module running on the RX3i backplane. If the PLC goes to
Stop Mode, or the CPU is lost due to over temperature or a watchdog timeout, the PSM
continues to operate with the last directive received from the CPU. If the CPU had requested
the synchronization of Grid 1 and Grid 2, when all sync parameters are met, the PSM will
assert RelayCloseOK and close its relay output contacts, even when the PLC is in Stop Mode.
Care must be taken to leave the Sync request in a known state when transitioning to stop
mode.
When Grid 1 and Grid 2 are synchronized, the PSM cannot be reset or cleared, and it will not
accept a new hardware configuration from the CPU. Once synchronized, the PSM can only
be cleared in preparation for receiving a new configuration by first commanding the PSM to
release the grid synchronization (simultaneously set %Q offset 16 to 1, and clear %Q offset
32 to 0), or by removing power from the PSM module. Mission Critical applications must
have a redundant PSM system to take over the grid synchronization from the Primary PSM
if the primary controller can no longer perform its function.
1.8.2 Frequency Measurement
Healthy three-phase power systems produce three almost identical sinusoidal voltage
waveforms that swing from positive to negative voltage at a frequency of either 50 or 60
times per second (50–60Hz).
The PSM determines the frequency of the power line by looking for the zero crossings, which
are places where the voltage crosses zero volts going from positive to negative or from
negative to positive. Only phase A voltages are used for the zero-crossing detection, so
phase A must be always present on one or the other grid.
Figure 4

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PSM Module Description and Specifications 9
Frequency Measurement Notes
PSM preferentially chooses Grid 1 VA zero crossing as the reference for signal sampling.
In the absence of Grid 1 VA, PSM uses Grid 2 VA zero crossing.
In the absence of either VA signal, grid frequencies will be reported as 0Hz, and the
remaining inputs will be sampled at a rate of 128 samples per 25ms. New data will be
updated at 25ms intervals. This may create sporadic looking individual readings, but a 10-
cycle average will be fairly steady and accurate.
When the difference in frequency between Grid 1 and Grid 2 is large, the Grid 2 RMS
readings will vary from cycle to cycle, however a 10-cycle average will be fairly steady and
accurate.
1.9 ANSI Functions Supported
The Grid 1 and Grid 2 functions are similar, but with differences in implementation. Grid 1 is
assumed to be the most stable power source, such a utility. Grid 2 is assumed to be a less
stable power source, such as a back-up generator. Either or both grids can be connected for
load monitoring, such as motors, lighting, HVAC or server room power.
1.9.1 ANSI Functions for GRID 1 (Public Grid/Load) Protection
ANSI 27 –Under-voltage Protection
Under-voltage Protection monitors voltages to protect motors against voltage sags. The
PSM monitors the phase-to-phase voltage in a delta power system, or phase-to-neutral
voltage in a wye power system, as a percentage of the Nominal Voltage parameter. An alarm
will be triggered if any voltage falls below the specified UNDER_VOLT_THR value for a time
period longer than UNDER_VOLT_DELAY. The alarm is cleared when the grid voltage rises
above the UNDER_VOLT_THR value for a time period longer than UNDER_VOLT_DELAY.
The UNDER_VOLT_THR is a percentage of the nominal voltage.
ANSI 32 –Reverse Power Protection
Reverse Power Protection provides protection from excessive reverse active power
produced by motors running as generators (supplying power). An alarm will be triggered if
a circuit’s active power exceeds the REV_PWR_THR for a time period longer than
REV_PWR_DELAY. The Alarm will be cleared when the active power exceeds the
REV_PWR_THR for a time period longer than REV_PWR_DELAY. The REV_PWR_THR is a
percentage of the nominal power, which in a 3-phase system, is three times the nominal
voltage multiplied by the nominal current.
ANSI 47 –Voltage Phase Sequence Protection
This function monitors the sequence of the phase A, B and C voltages. Detection of a wrong
sequence (A, C, B for example) triggers an alarm.
An entire cycle of waveforms is required to make this Phase Sequence determination. There
is no user settable delay parameter, so the moment a Phase Sequence error is detected, the
alarm is set. In both systems (Delta and WYE), the signal at the VA terminal is expected to
lead the signal at the VB terminal by 120 degrees. The signal at the VB terminal is expected

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PSM Module Description and Specifications 10
to lead the signal on the VC terminal by 120 degrees. Unused “reconstructed” signal inputs
are ignored for Phase Sequence detection. The current signals are not monitored for Phase
Sequence.
ANSI 50 –Instantaneous Over-current Protection
This function provides three-phase protection against overloads and phase-to-phase short-
circuits. An alarm will be triggered if any phase current exceeds the specified OVER_CURR_
THR value for a time period longer than OVER_CURR_DELAY. This alarm is cleared when the
current value stays below the OVER_CURR_THR value for a time period longer than
OVER_CURR_DELAY. The OVER_CURR_THR is a percentage of the nominal current.
ANSI 59 –Over-voltage Protection
This function provides detection of abnormally high phase voltage. It works with phase-to-
phase voltage in delta power systems, or phase-to-neutral voltage in wye power systems.
Each voltage is monitored separately. An alarm will be triggered if any voltage exceeds the
specified OVER_VOLT_THR value, as a percentage of the Nominal Voltage parameter, for a
time period longer than OVER_VOLT_DELAY. This alarm is cleared when the voltage drops
below the OVER_VOLT_THR value for a time period longer than the OVER_VOLT_DELAY.
The OVER_VOLT_THR is a percentage of the nominal voltage.
ANSI 60 –Voltage (Current) Imbalance Protection
An alarm will be triggered if any phase voltage or current reading varies from the average of
all three phases by more than VI_IMBALANCE_THR for a time period longer than
VI_IMBALANCE_DELAY. The alarm is cleared when the imbalance condition is corrected for
a time period longer than VI_IMBALANCE_DELAY. IV_IMBALANCE_THR is a percentage of
the average of the three phase voltages (for voltage imbalance) or the three phase currents
(for current imbalance) on a given grid. It works with phase-to-phase voltage in Delta power
systems, or phase-to-neutral voltage in WYE Power systems. No comparison is performed
between the two grids. Neutral current is not monitored for imbalance.
ANSI 81U –Under-frequency Protection
Detection of abnormally low frequency compared to the nominal frequency, to monitor
power supply quality. An alarm will be triggered if a circuit’s frequency falls below the
nominal frequency minus the UNDER_FRQ_THR for a time period longer than
UNDER_FRQ_DELAY. The alarm is cleared when the frequency rises above the nominal
frequency minus UNDER_FRQ_THR for a time period longer than UNDER_FRQ_DELAY.
UNDER_FREQ_THR is an absolute frequency, in Hz, that is subtracted from the nominal
frequency to determine the lowest acceptable frequency for the grid.
ANSI 81O –Over-frequency Protection
Detection of abnormally high frequency compared to the nominal frequency, to monitor
power supply quality. The alarm will be triggered if a circuit’s frequency is above the nominal
frequency plus OVER_FRQ_THR for a time period longer than OVER_FRQ_DELAY. The alarm
will be cleared when a circuit’s frequency falls below the nominal frequency plus
OVER_FRQ_THR for a time period longer than OVER_FRQ_DELAY. OVER_FREQ_THR is an
absolute frequency, in Hz, that is added to the nominal frequency to determine the highest
acceptable frequency for the grid.

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PSM Module Description and Specifications 11
ANSI Functions for GRID 2 (Generator/Generator Grid)
Protection
WARNING
It is the responsibility of the user to verify that the system has sufficient frequency stability
to maintain the current phase trend during the synchronization process. This requirement
is especially true for long breaker delays. Failure to maintain frequency stability during
synchronization may result in personal injury, equipment damage, or both.
ANSI 25 –Generator & Public Grid Synchronization
The PSM module can synchronize two sources from either a static phase angle or a rotating
phase angle.
In static phase angle synchronization, the overall PLC control system holds the two grids at
the same amplitudes, frequencies and phase angles, and then requests that the PSM
module synchronize the grids. To select this mode, set the Breaker Delay parameter to 0ms.
In rotating phase angle synchronization, the overall PLC control system holds the two grids
at the same amplitudes while keeping the frequencies at slightly different values so the two
grids gradually go in and out of phase. The PLC then requests that the PSM module
synchronize the grids whenever it is safe to do so. To select this mode, set the Breaker Delay
parameter to the non-zero value that corresponds to the time required for the
synchronization contacts to close. See “ANSI Protection Parameters” in chapter 3 for more
details on setting the breaker delay.
For safe synchronizing (i.e. connecting the generator grid with the public grid), in addition
to having no faults in either the public or generator grids, the following three parameters
must be within their specified limits:
•voltage matching (Delta Voltage between public grid and generator grid, all measured
phase voltages considered)
•frequency difference (Delta Frequency between public grid and generator grid).
•angle (Phase Shift between public grid and generator grid —using phase A voltages)
Voltage Matching
For synchronization, the Grid 2 RMS voltage must be within ±DELTA_VOLT_THR of the Grid
1 RMS voltage. DELTA_VOLT_THR is a percentage of the measured Grid 1 voltage. There is
no delay for setting or clearing this DeltaVoltOK status bit.
Voltage Matching
For synchronization, the Grid 2 frequency must be within ±DELTA_FREQ_THR of the Grid 1
frequency. DELTA_FREQ_THR is an absolute frequency difference in Hz.

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PSM Module Description and Specifications 12
Phase Angle
For synchronization, the two grids must be connected when the phase angle difference
between the grids is in the range of ±PHASE_SHIFT_THR, and ideally at the point when the
two grids are exactly in phase. The phase shift threshold represents an angle window in
electrical degrees (usually ±10°) around the 0° value, where it is safe to connect the two
grids. The phase shift between the grids can be a rapidly changing value in a rotating system.
Additionally, the breaker delay can be significant (hundreds of milliseconds). Therefore, in
rotating phase synchronization, the moment for commanding the sync relay to close must
shift forward to compensate for the time it takes for the contacts to close. For example, the
window of opportunity for commanding relay closure could happen between 25° and 15°,
in order for the contacts to close when the grids are truly in-phase. This angle offset is a
function of the frequency difference (and therefore the rate of change of the phase shift)
and the breaker delay.
Once the CloseRelayOK bit is set, it remains set until either the breaker delay + 24 power
cycles passes, or the phase shift enters and then leaves the ±Phase_Shift_Thr window. This
gives the contacts time to settle, and the two grids time to stabilize into synchronization.
Angle Delay
Angle Delay is a value, in degrees, that accounts for both the rate of change of the phase
shift between the grids and the breaker delay. Angle Delay is the angle through which the
synchroscope needle travels between the moment the PSM sets the CloseRelayOK bit to
close the IC694ACC200 relay contacts, and when the physical contacts on the sync relay
actually close:
Angle Delay = (360⁰x ΔF x Bdly)
Where:
ΔF = Grid 2 Frequency –Grid 1 Frequency
Bdly = breaker delay in seconds
The Breaker Delay PSM configuration parameter must include all the delays introduced
between the PSM module and the synchronizing contacts. For example, the IC694ACC200
Terminal Assembly relay outputs have a turn on time of 20ms (see “Specifications” on page
5), and a given contactor has a published closing time of 80ms.
The Breaker Delay parameter should be set to the sum of all delays, or 100ms in this
example. Ideally, the actual breaker delay time will be measured during installation
commissioning and used in the application to compensate for component variations.
Slow Rotating Phase Angles
In rotating phase angle synchronization, the PSM sets and clears the PhaseShiftOK status bit
based on the Angle Delay value. In slowly rotating phase angles where Angle Delay ≤
(Phase_Shift_Thr - 2º)/2, noise-induced jitter in the zero-crossing detection can make the
phase angle difference from one power line cycle to the next appear to change direction.
For this reason, 2º of hysteresis is added to the trailing edge of the PhaseShiftOK window:

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PSM Module Description and Specifications 13
PhaseShiftOK = On @ Angle Delay
PhaseShiftOK = Off @ –(Angle Delay+2º)
Figure 5 Slow Rotation: Angle Delay ≤ (Phase_Shift_Thr - 2º)/2
If the request to sync is on or received by the PSM module at any time in the green region
(while PhaseShiftOK = on), the CloseRelayOK status bit will be set and the IC694ACC200
output contacts will close.
Once CloseRelayOK is on and the IC694ACC200 output contacts are closed, they remain on
and closed, regardless of grid alarms, until after the breaker delay plus 24 power line cycles
pass, to allow the newly synchronized grids to settle. After the settling time, all ANSI
protections are reinstated and the PSM monitors the Delta Frequency, Delta Voltage and
Phase Shift status bits again.
In the absence of other alarms, the phase shift is allowed to drift within the phase shift
threshold (the yellow region) indefinitely as the PSM waits for the physical contacts to
synchronize the grids.
Example: Angle Delay ≤ (Phase_Shift_Thr - 2º)/2
Phase_Shift_Thr = 10º
Breaker Delay = 200ms
Grid 1 Frequency = 60.00Hz Grid 2 Frequency = 60.01Hz ΔF (slip frequency) = 0.01Hz
Angle Delay = (360º x 0.01Hz x 0.200sec) = 0.72º
PhaseShiftOK = On @ 0.72º {Angle Delay}
PhaseShiftOK = Off @ -2.72º {-(Angle Delay + 2º)}
If Sync is requested while PhaseShiftOK = On, then CloseRelayOK will be set to On
for the Angle Delay + 24 cycles. At ΔF = 0.01HZ and 60Hz, the PhaseShiftOK window
is 200ms (0.72⁰) + 400ms = 600ms.

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PSM Module Description and Specifications 14
Fast Rotating Phase Angles
For faster rotating phase angles where Angle Delay > (Phase_Shift_Thr - 2º)/2, these
equations apply:
PhaseShiftOK = On @ Angle Delay
PhaseShiftOK = Off @ Angle Delay –Phase_Shift_Thr
Figure 6 Fast Rotation: Angle Delay > (Phase_Shift_Thr - 2º)/2
If a request to sync is on or received by the PSM module at any time in the green region
(while PhaseShiftOK = on), the CloseRelayOK status bit will be set and the IC694ACC200
output contacts will close.
Once CloseRelayOK is on and the IC694ACC200 output contacts are closed, they remain on
and closed through the green, orange and yellow regions, regardless of grid alarms, until
after the breaker delay plus 24 power line cycles pass, to allow the newly synchronized grids
to settle. After the settling time, all ANSI protections are reinstated and the PSM monitors
the Delta Frequency, Delta Voltage and Phase Shift status bits again. In the absence of other
alarms, the phase angle is allowed to drift within the phase shift threshold (the yellow
region) indefinitely as the PSM waits for the physical contacts to synchronize the grids.
Example: Angle Delay > (Phase_Shift_Thr - 2º)/2
Phase_Shift_Thr = 10º
Breaker Delay = 800ms
Grid 1 Frequency = 60.00Hz
Grid 2 Frequency = 60.09Hz
ΔF (slip frequency) = 0.09Hz
Angle Delay = (360º x 0.09Hz x 0.800sec) = 25.9º
PhaseShiftOK = On @ 25.9º {Angle Delay}

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PSM Module Description and Specifications 15
PhaseShiftOK = Off @ 15.9º {Angle Delay –Phase_Shift_Thr}
If Sync is requested while PhaseShiftOK = On, then CloseRelayOK will be set to On
for the Angle Delay + 24 cycles. At ΔF = 0.09Hz and 60Hz, the PhaseShiftOK window
is 800ms (25.9⁰) + 400ms = 1.2 seconds.
Static Phase Angle Synchronization
In static phase angle synchronization, the PSM will set PhaseShiftOK bit between
±Phase_Shift_Thr, regardless of the Delta Frequency (Slip Frequency). This mode is selected
by setting the Breaker Delay hardware configuration parameter to zero.
Figure 7
With no breaker delay information, the PSM reverts to classic synchronization. Either the
control system holds the phase angle within the Phase_Shift_Thr before requesting
Synchronization, or the rate of change of the phase angle and the breaker delay are known
and the control system holds the Delta Frequency (Slip Frequency) at a value calculated to
bring the contacts to closure at or near 0⁰phase angle.
ANSI 27 –Under-voltage Protection
This function monitors voltages to detect abnormally low grid voltage. It works with phase
to-phase voltage in delta power systems, or phase-to-neutral voltage in wye power systems.
Each phase voltage is monitored separately. An alarm will be triggered if any voltage falls
below the specified UNDER_VOLT_ THR voltage value for a time period longer than
UNDER_VOLT_DELAY. The alarm Is cleared if any voltage rises above the specified
UNDER_VOLT_ THR voltage value for a time period longer than UNDER_VOLT_DELAY. The
UNDER_VOLT_THR is a percentage of the nominal voltage.
ANSI 32 –Reverse Power Protection
Reverse Power Protection prevents the generator from motoring on loss of the prime
mover. An alarm will be triggered if the prime mover power falls below the REV_PWR_THR
for a time period longer than REV_PWR_ DELAY. The alarm will be cleared when the prime

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PSM Module Description and Specifications 16
mover power rises above the REV_PWR_THR for a time period longer than REV_PWR_
DELAY. The REV_PWR_THR is a percentage of the nominal power which, in a 3-phase
system, is three times the nominal voltage multiplied by the nominal current.
ANSI 47 –Voltage Phase Sequence Protection
The sequence of the phase A, B and C voltages is monitored. Detection of a wrong sequence
(A, C, B for example) will trigger an alarm.
ANSI 50 –Instantaneous Over-current Protection
Provides three-phase protection against overloads and phase-to-phase short-circuits. The
alarm will be triggered if any phase current exceeds the specified OVER_CURR_ THR voltage
value for a time period longer than OVER_CURR_DELAY. The OVER_CURR_THR is a
percentage of the nominal current.
ANSI 59 –Over-voltage Protection
This provides detection of abnormally high phase voltage. It works with phase-to-phase
voltage in Delta power systems, or phase-to-neutral voltage in WYE Power systems. Each
voltage is monitored separately. An alarm will be triggered if any voltage exceeds the
specified OVER_VOLT_THR value, as a percentage of the Nominal Voltage parameter, for a
time period longer than OVER_VOLT_DELAY. This alarm is cleared when the voltage drops
below the OVER_VOLT_THR value for a time period longer than the OVER_VOLT_DELAY.
The OVER_VOLT_THR is a percentage of the nominal voltage.
ANSI 60 –Voltage (current) Imbalance
An alarm will be triggered if any phase voltage or current reading varies from the average of
all three phases by more than VI_IMBALANCE_THR for a time period longer than
VI_IMBALANCE_DELAY. The alarm is cleared when the imbalance condition is corrected for
a time period longer than VI_IMBALANCE_DELAY. IV_IMBALANCE_THR is a percentage of
the average of the three phase voltages (for voltage imbalance) or the three phase currents
(for current imbalance) on a given grid. It works with phase-to-phase voltage in Delta power
systems, or phase-to-neutral voltage in WYE Power systems. No comparison is performed
between the two grids. Neutral current is not monitored for imbalance.
ANSI 81U –Under-frequency Protection
Detection of abnormally low frequency compared to the nominal frequency, to monitor
power supply quality. An alarm will be triggered if a circuit’s frequency falls below the
nominal frequency minus the UNDER_FRQ_THR for a time period longer than
UNDER_FRQ_DELAY. The alarm is cleared when the frequency rises above the nominal
frequency minus UNDER_FRQ_THR for a time period longer than UNDER_FRQ_DELAY.
UNDER_FREQ_THR is an absolute frequency, in Hz, that is subtracted from the nominal
frequency to determine the lowest acceptable frequency for the grid.