LORAIN POWER PLANT

By Ajay Singh.

AGENDA Brief Description.

Installation.• Physical Considerations.• Electrical Connections.

Operation, Settings & Adjustments.• Rectifier Module.• Microprocessor Controlled Meter Panel. • Redundant Low Voltage Disconnects.• High Voltage Shutdown.

Brief Description

The LORAIN 1231A2 Power System is a –48V DC power system having a maximum current capacity of 50 to 300 amps, which is designed for use with FLOTROL rectifiers and limited maintenance batteries.

Its equipped with a microprocessor controlled meter panel, which displays battery voltage and load current through the seven segment LCD display, activates local visual and remote alarms, permits automatic and manual equalize charging after the power interruption and subsequent battery discharge.

It consists of two LVD’s which disconnect the noncritical and critical load at 44.5V and 42V respectively & reconnect at 49V.

INSTALLATION

Physical Considerations

The rectifier is a 23 inch wide relay rack, 2.13 m in height. The distance from the rear should not be less than 6 inches. This shelf should be mounted such that the front & rear ventilation openings are not blocked and the temperature of air entering the shelf does not exceed beyond the temp range (-40C to + 65C). The rectifier is capable of operating in an ambient relative humidity range of 0 to 95%(non condensing).

Electrical Connections•The AC Input connections:

The AC input and frame ground connections are made to a terminal block TB1, which is located inside the rectifier shelf at the lower left hand side of the rear panel. The AC wiring is fed through a rectangular opening at the rear of the left side panel.

The input connections to all rectifiers are made on the terminal blk TB1. Input connections to all modules must be done at this time, including the currently unused position.

R phY phB ph

TB 1

Mod 1

Mod 2

Mod 3

AC input

To

Rect

Mod

The DC connections:

The Battery - ve terminal is connected to the circuit breaker panel, and the + ve terminal to the + ve bus bar in the DC distribution panel.

The DC output of each rect is connected in parallel to a DC output supply terminal located on the right side of the shelf. The DC output +ve & - ve terminal is then connected to the + ve & - ve bus bar in the DC dist panel.

Operation, Settings & Adjustments

• Rectifier Module:

The rectifiers are housed in a rectifier ring shelf, which can hold max 6 rectifier modules, each with the following ratings:

Range Factory Setting

Float voltage From 48 v to 58 v DC. 54.48 V DC.

Equalize voltage From 53 v to 60 v DC. 56.00 V DC.

AC input voltage From 150 v to 290 v AC. -

Current Limiting From 50% to 105% of 50 A.

50A.

Frequency 47 to 70 Hz. -

Temperature -40 to 65 deg Celsius -

Every rectifier module consists of following controls and indicators:

DC

Output

+

-

-

+

Rect

Volt

Out

CurCurrent Limit

Float

EQ

HVSD

RectTest

On

Off

On

Off

AC Input

AC on

Open SNS

RFA

FAN FAIL

50

40

30

20

10

Rect

Cur

(Amps)

CONTROLS INDICATORS TEST JACKS

AC I/P CKT Breaker AC ON Indicator Rect Volt

DC O/P CKT Breaker OPEN SNS(Open O/P ckt breaker) Out cur

Current Limit Potentiometer RFA (Rectifier fail alarm) Rect Test

Float Potentiometer FAN FAIL alarm -

Equalize (EQ) Potentiometer Rectifier current o/p indicator -

High Voltage Shutdwn (HVSD)Pot - -

Float voltage adjustments

REPEAT FOR ALL MODULES IN THE SYSTEM

NO YES

START

CHECK IF SYS IS IN FLOAT ?

PUT SWITCH S1 IN OFF/RESET POSITION

ALLOW VOLTAGE TO STABILIZE

CONNECT DMM TO THE “RECT VOLT” TEST POINT

FIRST SWITCH OFF AC I/P CKT BREAKER THEN THE DC O/P CKT BREAKER TO THE OFF POSITION. THEN SWITCH ON THE AC I/P CKT BREAKER. IF IT TRIPS THEN AGAIN SWITCH ON THE AC IP CKT BREAKER

ADJUST THE POT ‘FLOAT’ EITHER IN CLOCKWISE OR IN ANTICLOCKWISE DIRECTION TO GET THE DESIRED FLOAT VOLTAGE.

ALLOW VOLTAGE TO STABILISE

STOP

Similarly, for equalize voltage adjustment, one has to rotate the EQ pot on the module to get the desired Equalize voltage.

If the rectifiers are not sharing equal load in float mode then the following procedure should be carried out:

For load sharing in Equalize mode, one has to put the rectifier in Equalize mode and rotate the EQ pot.

Load sharing adjustments

NO YES

START

CHECK IF SYS IS IN FLOAT ?

PUT SWITCH S1 IN OFF/RESET POSITION

ALLOW VOLTAGE TO STABILIZE

ADJUST THE POT ‘FLOAT’ OF THE RECTIFIER DRAWING THE LOWEST CURRENT & THEN THE POT OF OTHER MODULES IF NECESSARY TILL THE RECT CURRENT INDICATOR SHOWS EQUAL

CURRENT IN ALL MODULES.

STOP

START

CONNECT DMM TO THE “OUT CUR” TEST POINT

Operate & hold the “RECT TEST” switch on the module under test to the up position. This module will then try to deliver full load. But if the load is not greater than the total current

capacity then the rectifier will not go into current limit & hence resistive load will have to be connected.

Check the reading of DMM, eg if its 1mv then o/p current is 1A. This is the current limit setting to increase or decrease the current limit setting adjust the pot “Current Limit”

clockwise or anticlockwise

When desired current limit setting is reached remove “Rect Test” switch.

STOP

Current Limit Adjustments: The potentiometer “Current limit” sets the point to which rectifier output is limited.

High voltage shutdown adjustment:

Every rectifier module is factory adjusted for a high voltage shutdown point of 59.5 volts. Changing the potentiometer HVSD sets the rectifier module to a new desired high voltage shutdown voltage level.

The Microprocessor controlled meter panel

The microprocessor controlled meter panel is designed to operate between – 42 to –56 V DC. It provides an indication of battery voltage, and total load current. It consists of following controls and indicators:

Seven segment LCD display

MN HVA2 LVA2 FA ACO

MJ HVA1 LVA1 SET EQU

+ -DISCHARGE VOLTS

INDICATORS

OFF / Reset MAN Volts Set

ON AMPS INC DEC SEL ACO

CONTROLS

Auto Equalize Meter Select

Switch S1 Switch S2

• CONTROLS:

1) Switch S1: This three position rocker switch selects the mode of equalize control as follows:

a) OFF/Reset: S1 pressed to this position causes cancellation of the current equalize cycle. b) ON: S1 pressed to this position enables the automatic equalize timer circuit. c) MAN: S1 pressed to this position manually places connected rectifiers in equalize charge

mode.

2) Switch S2: This three position rocker switch selects the mode of meter operation as follows: a)VOLTS: S2 pressed to this position indicates voltage at the discharge bus is displayed on

the meter face. b) AMPS: S2 pressed to this position indicates load current, which is displayed on the meter

panel. c) SET: S2 pressed to this position allows the alarm and control functions of the meter panel

to be set to their desired limits.

3) Alarm Cut Off (ACO): This momentary push button switch cancels an audible minor alarm.

4) Select Switch(SEL): When Switch S2 is in the SET mode, this momentary pushbutton switch selects the various alarm and control functions.

e) Decrement Switch (DEC): This momentary pushbutton switch decreases the set point of the function indicated on the meter face.

f) Increment Switch (INC): This momentary pushbutton switch increases the set point of the function indicated on the meter face.

• INDICATORS:

a) Fuse Alarm (FA): This red LED illuminates is any fuse connected to the fuse alarm input leads should open.

b) Major Alarm (MJ): This red LED illuminates if two or more rectifier alarms or ring shelf major alarm or fuse alarm failures are detected.

c) Minor Alarm (MN): This red LED illuminates if one rectifier fail alarm, ring shelf minor alarm, or CPU failure alarm in meter panel is detected.

d) Low voltage alarm 1 (LVA1): This red LED illuminates if the battery voltage decreases below a first low preset limit.

e) Low voltage alarm 2 (LVA2): This red LED illuminates if the battery voltage decreases below a second low preset limit.

f) High Voltage Alarm 1 (HVA1): This red LED illuminates if the battery voltage increases above a first high preset limit.

g) High Voltage Alarm 2 (HVA2): This red LED illuminates if the battery voltage increases above a second high preset limit.

h) Alarm cut off (ACO): This yellow LED illuminates when the ACO switch is pressed to indicate a minor audible alarm has been cancelled.

i) SET mode (SET): This yellow LED illuminates when S2 is placed in set position indicating set mode.

j) EQ (Equalize): This yellow LED illuminates when meter panel is in the equalize mode.

•Adjustments:

The Microprocessor operates Seven alarm relays, HVA2, HVA1, LVA2, LVA1, MJ, MN, & FA. Each relay provides contacts for customer connection of external alarms. The control and alarm settings may be adjusted by performing the following procedures:

Low Voltage Alarm 1(LoA1): For setting LVA1limit, place the switch S2 to SET position & press SEL button repeatedly till LoA1 is displayed on the Seven Segment display.

After a short time delay, the numerical equivalent set point is displayed. To increase or decrease the level at which the alarm will be generated push the INC or DEC button until desired level is indicated. Once the desired level is achieved remove the switch S2 from the SET position and resume the normal operation.

Low Voltage Alarm 2(LoA2): For setting LVA2limit, repeat the above procedure by placing the switch S2 to SET position & pressing SEL button till LoA2 is displayed, and changing the numerical equivalent to the one desired.

Similarly for setting HVA1 & HVA2 the SEL button should be pressed till HiA1 & HiA2 is displayed, and pressing INC or DEC button the desired numerical value should be set.

Automatic/ Manual Equalize Control Circuit:

The automatic/ manual equalize control circuit provides automatic or manual control of the equalize charge mode of the rectifiers in the associated power system. In auto mode the circuit puts the rectifier in equalize mode when power resumes after power failure or when the battery voltage decreases below discharge threshold value(which is factory adjusted to 53.65 V).

When there is a power failure, a timing circuit is activated (discharge cycle), after the power resumes the equalize control circuit places the rectifiers in equalize mode of operation for a duration which is a multiple of the discharge cycle.

Equalize on Discharge Threshold Adjustment (Ethr)

The equalize on discharge threshold sets the point at which battery voltage has decreased below the preset limit and activates the automatic equalize circuit.

For setting the threshold level by placing the switch S2 to SET position & pressing SEL button till Ethr is displayed, and changing the numerical equivalent till the one desired is achieved.

Equalize Time Multiple Adjustment(Escl)

The equalize time multiple adjustment sets the duration of equalize time, .

Time for which the system is in Equalize mode = (Time of power fail) x (Escl).

For setting the threshold level by placing the switch S2 to SET position & pressing SEL button till Escl is displayed, and changing the numerical equivalent till the one desired is achieved.

Alarm or Control Circuit

Factory Setting Adjustment range

Low voltage alarm 1 53.65 v DC 0 to 99.99

Low voltage alarm 2 48.25 v DC 0 to 99.99

High voltage alarm 1 55.40 v DC 0 to 99.99

High voltage alarm 2 58.40 v DC 0 to 99.99

Equalize Time Multiple

3 0 to 15

Equalize time on Discharge Threshold

53.65 v DC 0 to 99.99

This meter panel provides extended relay contacts which may be used to activate various external alarms.

•External Alarm Connections:

J12

J13

J10

J11

J8

J9

J6

J7

J5J4

1 1 1 1

1111

1

1

9

9 9 9 9

9999

9

14

Alarm

Designation

FA LVA

1

LVA 2 HVA 1

HVA 2

MJ MN LVD

MJ

LVD

MN

Relay contacts close

between

2-3,

5-6,

8-9

2-3,

5-6,

8-9

2-3,

5-6,

8-9

2-3,

5-6,

8-9

2-3,

5-6,

8-9

2-3,

5-6,

8-9

1-2,

4-5,

7-8

2-3,

5-6,

8-9

2-3,

5-6,

8-9

Redundant Low Voltage Disconnects

The Lorain Power Supply System consists of two Low Voltage Disconnects, Critical & Non Critical LVD. Each LVD is governed by two circuits 1 main(Circuit A) and the other redundant(Circuit B) to disconnect the load from battery if battery voltage decreases below a preset adjustable disconnect level, as in during the power failure.

Ckt A

Ckt B

Pot for setting turn on voltage

Pot for setting cut off voltage

R3

R5

R19

R17

Reconnect Switch S1

Alarm

LED

Alarm

LED

The point where the LVD disconnects the load can be set by varying the pot R5 & R17. And the point where the LVD reconnects the load can be set by varying the pot R3 & R19.

When both circuits sense a low voltage condition, a disconnect will be initiated , and an external alarm indication is extended. Reconnect is initiated if either detector circuit senses the turn on voltage.

High Voltage Shutdown Circuit

The high voltage shutdown circuit supplies a shutdown signal to the rectifier modules if the battery voltage increases above an adjustable preset level.

Alarm

LED

R2 HVSD potentiometer

TEST Circuit push button

TEST point + ve

TEST point - ve