Introduction; About This Manual; Features Of The Mj-4A & Mj-4B Control Panels - Siemens MJ-4A Installation And Operation Manual

1 Introduction

(TM)
The MJ-4A and MJ-4B
(TM)
lectively as MJ-4 is a Voltage Regulator Control Panel,
which is a members of the Siemens Accu/Stat® series of
digital controls, designed for use with many regulators and
load tap changer models.
Although the MJ-4 Control Panel includes some new func-
tions, its operational characteristics are similar to those of
earlier-model Accu/Stat MJ-1A, 2A, 3, 3A, MJ-X, and MJ-
XL controls. It is electrically and mechanically interchange-
able with these controls.
Voltage Reduction Control, Voltage Limit Control, six
Power Flow modes, and Data Logging are all standard fea-
tures of the MJ-4 Control Panel.
In addition to manual and automatic voltage monitoring
and control, the MJ-4 Control Panel also offers full remote
monitoring and control capability. Via a communications
link, a remote operator can monitor operating conditions
and adjust setpoints or command tap changes—just as if
he/she were locally operating the controls.
When equipped with an optional Communications Mod-
ule, the MJ-4 Control Panel provides remote communica-
tions and SCADA (Supervisory Control And Data
Acquisition) compatibility. Please refer to the MJ-4 Com-
munications Module Installation Manual for an in-depth
treatment of the Communications Module.
The regulator control function has two operating modes—
manual and automatic. Remote control can be enabled or
disabled for each of these operating modes. The operating
modes and remote control settings are described in Sec-
tion 2.5.
• Manual control. In Manual mode, the operator
directly controls the regulator tap changer and uses
this mode to enter regulator setpoints for automatic
control.
• Automatic control. In Automatic mode, the micro-
processor controls the regulator tap changer, based
on setpoints stored in memory.
• Remote control. If enabled, this setting permits a
remote operator to change operational values and
setpoints as well as to monitor operational values. If
disabled, a remote operator can only monitor opera-
tional values.
1.1

About This Manual

This manual is designed to help you become acquainted
with all aspects of the MJ-4 Control Panel. The manual
starts with the operator panel and controls, followed by
physical installation considerations, setup procedures,
day-to-day operations, and finally, troubleshooting. The
Appendices provide further information about MJ-4 Con-
trol Panel operation and setup.
Siemens Energy, Inc.
(TM)
, here after referred to col- Note: This manual describes features embodied in
MJ-4 software version 4.10
1.2 Features of the MJ-4A & MJ-4B
Control Panels
This section briefly describes the standard MJ-4 Control
Panel features and functions.
Display Panel and Operator Controls
Operator input to the MJ-4 Control Panel is accomplished
through a set of touch-keys. MJ-4 output is presented in
plain text through a sixteen-character alphanumeric dis-
play panel. For status items, such as Voltage Reduction
and Voltage Limit, indicators provide a quick-glance sum-
mary of MJ-4 Control Panel operating conditions.
Metering
The MJ-4 Control Panel maintains and presents opera-
tional data to help you monitor system operation. Instanta-
neous and demand values (along with minimum and
maximum for each) are readily available.
Data Logging
The Data Logging function maintains historical data for
subsequent review and analysis. This data can be very
useful in the assessment of load characteristics by time of
day or season; the reconstruction of system problems;
and the improvement of the overall efficiency of the power
distribution system.
Voltage Limit Control
Voltage Limit Control (VLC) automatically maintains regula-
tor output voltage within preset high and low limits.
Line Drop Compensation
Line Drop Compensation (LDC) models the resistive and
reactive voltage drop of the line. The resulting model is
used by the microprocessor to correct regulator output
voltage for the effects of line drop between the regulator
and the load.
Voltage Reduction Control
Voltage Reduction Control (VRC) reduces output voltage
and can be activated automatically, manually, or remotely.
Reverse Power Flow Detection and Operation
In many systems, power only flows in one direction; how-
ever, in some systems power flow reverses from time to
time. To accommodate power flow reversal, the MJ-4
Control Panel monitors power flow direction and adjusts
its operation accordingly. Six different Power Flow Modes
allow flexibility in selecting a control algorithm which best
matches the power flow needs of the system.
1
Introduction
1