POWER PLANT- ISOLATED SHUNT AMPLIFIER MODULES(ISAM)

Isolated Shunt Amplifier Module (Isam)

 Introduction

A standard MiniCSU system only accepts Hall-effect current transducers with full scale output of ± 4V. In situations where current shunts are used in place of Hall-effect current transducers, the ISAM, or Isolated Shunt Amplifier Module can be used. It provides optical isolation and converts the ± 75mV current shunt full scale signal to the required ± 4V full scale signal. 
Electrical Specification

Power Supply                         ± 14Vdc to ± 16Vdc

Signal Input                             ± 75mV

Input Impedance                     650 W

Absolute Max Input                 ± 6V

Signal Output                          ± 4V (@ ± 75mV input)

Output Impedance                  1 kW

Output Short Circuit                Indefinite

Output Error                            Typically 0.1% of 4V FSD

Output Zero Offset                 Typically 0.1% of 4V FSD

Physical Specification

Board Dimensions                  approx. 116mm x 66mm

Signal Input Connector            2 pin male header 5.0mm pitch

Output Connector                   4 pin male header 2.54mm pitch

Input connections                    Shunt +, Shunt -

Output Connections                +15V, -15V, VOUT, GND

System Setup

The ISAM should be located as close as possible to the shunt, ideally within 1~2 meters of the shunt. It should also be mounted securely in a dry, dust free environment. The shunt should be wired up to 2 way Weco 5.0mm screw connector , polarity is shown below:

	To Shunt

 

Wire up a Molex 22-01-2045 Female connector with the following connections:

 

The other side of the 4-way cable can be connected either to the MUIB or MUIB2.

POWER PLANT- MINI USER INTERFACE BOARD(MUIB)

Mini User Interface Board (MUIB-2)

This PCB has on board provision for all the external connections to and from the MiniCSU –2 such as current and temperature transducers and remote alarms.  The module is connected to the MiniCSU - 2 via a 34-way ribbon cable.

All connecting lines which are sourced from outside of the rack containing the SMRs and MiniCSU terminate on the MUIB-2 where some filtering and protection in the way of fuses or series resistors are located.

 MUIB2 Connection Diagram

The MUIB2 connection diagram is illustrated below.

 

POWER PLANT- MINiCSU DESCRIPTION

MiniCSU-2 Description

The MiniCSU-2 Module is a very compact monitoring and control unit designed to operate with SMR rectifiers. It is 1U (44mm) high, 175mm wide and 265mm deep. It weighs less than 1 Kg.

The module comprises four subassemblies:

1)    The main circuit board MICSU

The main circuit board has the microprocessor and Peripheral circuits, analog interfacing circuit, Optocoupler interface circuit and the flyback switch mode supply

2)     A small front panel board MCFP1 which has the push-buttons and LEDs on it and the 16 character, two line LCD display which is also mounted on the front panel.

3)    Back plane of MiniCSU-2 magazine includes EEPROM card. All operating Parameters and alarm log are retained with the system in case of a need for the Controller  change.

4)    The fourth subassembly comprises a 9 pin D connector and RS232 driver for connection to a local PC.

POWER PLANT- RECTIFIER MODULE GENERAL DESCRIPTION

Rectifier Module General Description

The switch mode rectifiers (SMRs) are designed to be used in conjunction with a control and supervisory module (MiniCSU2).Operating parameters cannot be set or voltage and current displayed without using the CSU. Since the rectifiers are designed to operate in parallel in  redundant mode, it is never necessary to set individual rectifier parameters.

All electrical connections to the unit are made on the back plane via a single connector. Mating of the connector occurs automatically when a unit is inserted into its position in the specially designed magazine. Each magazine has 4 positions and fits a standard 19” rack. Installing and replacing rectifiers is easy and can be done by one person.

A bar graph display of output current on each rectifier is available as an option.

The rated input voltage for the module is 220Vrms. The tolerance is 90 – 300Vrms.

 General Operating Principles

This section describes in some detail the operating principles used in the design of the “Boost” and DC/DC power conversion stages as well as of the overall control and monitoring circuits.  The rectifier is made up of 5 printed circuit assemblies.

1)    Power Motherboard (PMB2): It has the following parts

·      EMI filter and inrush limiting circuit;

·      the AC/DC converter, a boost stage with loss less snubber;

·      a double ended forward converter to convert the regulated 420VDC from the boost 

           stage to 48V  (24V);

2)    Digital Secondary Control Card (DSCC)

It has the secondary side voltage and current feedback loops, and the microprocessor for controlling the rectifier and communication with the System Controller.

3)    Control Loop Card (CLC) With the feedback loops and the gate drives for the boost stage and the forward converter stage

4)    Primary Auxiliary Flyback Converter (PAFC) which plug directly into the motherboard This card provide power to the primary and secondary control circuits.

5)    Front Panel card (FP25A) fits into the plastic moulding at the front of the rectifier module and contains 3 status LEDs as well as optional bargraph LED display. It is connected to the DSCC inside the rectifier body by a 10 way ribbon cable. The rear panel connector (the only external connector) has the AC, DC and communication connections. Two additional pins are for sensing an address resistor at each rectifier location so that the microprocessor in the rectifier can tell at which location it is installed. An address resistor with a different value for each rectifier position is connected at the back of the magazine.