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G8MNY  > TECH     28.04.22 09:08z 237 Lines 11966 Bytes #12 (0) @ WW
BID : 885_GB7CIP
Read: GUEST
Subj: APC Smart 900 UPS
Path: SP7YDD<SR1BSZ<EA2RCF<ED2ZAE<F1OYP<N7HPX<W9GM<GB7YEW<GB7CIP
Sent: 220428/0844Z @:GB7CIP.#32.GBR.EURO #:885 [Caterham Surrey GBR] $:885_GB7C
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                                         (Update Dec 07)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

This is some info I have found out on this American Power Conversion UPS.
(Uninterruptable Power Supply)

SCHEMATIC                   v       v                        v
   ┌────┐┌─────┐┌──────┐ ┌──┴──┐┌───┴────┐ ┌───────────┐ ┌───┴───┐  ┌───┐
In>┤12A ├┤Spike├┤Mains ├┬┤ON OR├┤BOOST OR├─┤   Large   ├┬┤ Smpsu ├─┬┤Bat├>
IEC│Trip││Clamp││Filter│││ FAIL││ NORMAL ├┬┤Transformer││└───────┘ ││Mon│
   └────┘└─────┘└──────┘│└─────┘└────────┘│└───────────┘│┌────────┐│└───┘
                        │┌──────┐         │┌───────┐    └┤SM Sine ├┴<Batteries
                        └┤In Mon├>        ├┤Out Mon├>    │Inverter│
         v               └──────┘         │└───────┘     └───────┬┘
Out  ┌───┴───┐ ┌──────────┐ ┌─────┐       │    ┌─────────────┐   ^
4x<──┤LOAD ON├─┤Filter Cap├─┤I Mon├───────┘   >┤uProc Control├>
IEC  └───────┘ └──────────┘ └─────┘            └─────────────┘

The control sorts out what is the required state for the 3 relays (CAPITALS)
from the various monitoring function inputs. It also predicts battery life.

It is a switched UPS system, which means there is a very short break (10ms?) in
the output when the supply goes out of limits (fails) & the inverter cuts in.

MAINS CIRCUIT
              MAINS FILTERS          (Fail)    (Boost)
   Trip          L1         L2         RY3       RY2
L──o-o─┬──┬──┬──┐  ┌───┬──┐  ┌──┬──────o o───────o-o───┬─────┐
   12A │  │  │  │  │   │  │  │  F1     o/          o   │     │
       │  │  │  │  │   │  │  │  1A     └Inv Volt   └───)──┐___)║ __
MAINS  │ VDR │  ()))  === ()))  │        Mon           │      )║(   24 DC
INPUT VDR │ === ==== ┌─┤  ====  )║( Mains         ┌─F2─┤   T3 )║(__ INVERTER
E─┐    │  │1u│  ())) │=== ()))  )║( Mon    O/P )║(     │      )║    & CHARGER
  ┴    │  │  │  │  │ ┴ │  │  │  )║ T1      Mon )║(T2   │     │ 650W    │
       │  │  │  │  │   │  │  │  │               ║(     │     │         ┴
N──────┴──┴──┴──┘  └───┴──┘  └──┴─────────────────┴────)─────┤
                            RY1                        │     │
 ┌─────┬────┬────┬──────────o\o────────┬───────────────┘      )║( CT2
 L     L    L    L         (Load)       )║( CT1 Mon.         │ Current
 E──┐   OUTPUT                         │   Inverter          │ Mon.
 N  ┴  N    N    N                 4u7===  Current           │
 └─────┴────┴────┴─────────────────────┴─────────────────────┘

If the mains is just low, then RY2 is operated to obtain more voltage.

INVERTER
The 24V volt inverter uses a powerful bridged Class D 16 FET amp at many kHz.

   │║▓█▓║│         Phase 1     +24V HF pulses
   │║▓█▓║│                     fed via the 2 
~~~~~~~~~~~~~~~~~~~            FET outputs to
           │║▓█▓║│             each side of
           │║▓█▓║│ Phase 2     the transformer.
~~~~~~~~~~~~~~~~~~~
     .-.
    /   \                These pulses do not get through
   |     |               T3 & the 4u7 capacitor so the
  |       |       |      resultant filtered output is a
           |     |       rounded mean of those needle
            \   /        pulses to make a 50Hz sine wave.
             '-'
There are several feedback loops that control the output.
1) The 50Hz is locked in phase to the incoming supply when it is present so
   there is less of a voltage jump on changeover.
2) Output Voltage feedback ensures regulated voltage.
3) Over current alarms & then kills the inverter, protecting it from damage.

BATTERY CHARGING
The 24V charging system uses a SMPSU fed from T3 secondary. This "rings up" a
ferrite choke to reach the higher battery voltage something like this.

┌─┤>├─┬─┤>├─┬─()))─┬─────┤>├─┬─────┬───┬──>+
│    16V    │ ::::  \│  _____│_    │   │    27.4V
│     AC    │        ├─┤  SM   │  === ===   Charging
├─┤>├─┴─┤>├─┤      e/│ │ Drive │   │   │    Battery
│          ===     │   └─┬───┬─┘   │   │    2A max
└───────────┴──────┴─────┴─R─┴─────┴───┴──>-   

Batteries, as with most UPSs of the sort they are literally CAINED to get the
performance! So don't expect them to last long. On full discharge something
like 33 amps is drawn from 4 small 6V dry fit 11AH batteries. This is like
pulling your car starter for 5-10 mins! OK for the odd 2 second start, but not
for mains replacement. In my application these will be boosted by large
external batteries.

APPROX SPECIFICATION of APC SMART 900
=====================================
 Input          Option 1(1)2(1)3(1)4(0)   204-263V  48-56Hz
 Output         Option 2(1)   as input or 240V frequency locked to input
 Mains neutral always left connected unswitched
 Mains filter removes high frequency spike components (>10kHz 40dB)
 Mains clamp removes high voltage transients    (> 400V peaks @ 25Amps)
 Low mains is boosted with Smart Boost of 20V (step up auto transformer)
 Switch over time                     < 20mS ?
 Inverter type                         Class D bridged HF
 Output shape                          Sine wave output
 Power                                 630W max
 24V DC Lead Acid storage, 2x7AH       23V @ 33A load for 630W
 Charging up to                        2A @ 27.4V
 Size 18" Long, 7" Wide, 9.5" Tall, Weight 40lb (18kg)

           ______________________              To open remove bottom 2 rear
  REAR    /~~~~~~~~~~~~~~~~~~~~~/\   FRONT     screws & hinge top right up to
  PANEL  /=====================/ /│ CONTROLS   unhook front. This leaves the
 24V DC  │~~~~~~~~~~~~~~~~~~~~│\/ │    &       batteries & large transformer
Mains in │                    ││ /│INDICATORS  in the bottom & the PCB in the
   IEC   │- - - - - - - - - - ││/ │            top, connected by heavy leads.
Main out │                    ││ /      N.B. If you disconnect any of the
 4x IEC  │                    ││/       leads mark exactly where they are
         └────────────────────┴'        from as several have the same colour!

REAR SWITCH OPTIONS                           For UK use
SW    O       1          MEANING                0 <-> 1
 1  ˝ 10 %  ˝ 13 %     Sensitivity                    #
 2  230V   240V (+4%)  Voltage                        #
 3  1 Sec   30 Sec     Initial Alarm wait             #
 4  2 Min    5 Min ??  Batt Dead Warning        # (1 Seems to stop Options!)
Factory setting all 0s

OPERATION                                     REAR PANEL
=========                             ┌───────────────────────┐
Connections:                          │o/232\o[4321]          │
                                      │ ~~~~~ options         │
With the rear panel rocker ENABLE     │                       │
switch set to (0) off..               │                       │
                                      │                       │
                                      │ENABLE  Mains  MAINS IN│
                                      │  SW     (o)      [IEC]│
Connect the IEC mains input & up      │         Trip          │
to 4 IEC mains loads.                 │                       │
                                      │                       │
                                      │                       │
9 pin RS232 connection can be made    │                       │
with the right software. Connection   │     MAINS OUTPUTS     │
may override control buttons.         │[IEC] [IEC] [IEC] [IEC]│
                                      └───────────────────────┘
---------------------------------------------------------------------------
From Lod PA3BNX@PI8SHB.#NBO.NLD.EU
General rs232 control lines with a UPC.
Power Failure       CTS When mains fails.
Low battery         DCD Accu almost empty.
Remote UPS shutdown DTR Pc asks to switch UPC off.
You can use UPS in Control Panel from WINNT and XP Pro
---------------------------------------------------------------------------
Power up:    Switching the rear ENABLE to ON while pressing (1) test button
             will immediately switch the power on if the mains is present or
             not, & if mains is OK, a battery test with the LINE IN & BATTERY
             bargraph LEDs flashing while the system readies itself for 5 secs
             then the inverter test runs for 10 secs.
              ┌─────────────────────────────────────────────────┐
              │   []                  .˙.                  []   │
         FRONT│   []                 ( 1 )                 []   │
              │   []                 test                  []   │
      CONTROLS│   []                                       []   │
              │   []     []     []    .1.    []     []     []   │
              │   []     On    On    ( 0 ) Smart Replace   []   │
              │  Load   Line  Battery '˙'  Boost Battery Battery│
              └─────────────────────────────────────────────────┘
             The green mains ON LINE LED will be flashing in test node (if
             there is mains present), & the yellow ON BATTERY LED will be on.
             After the 10 second test it will switch back to the mains if it
             is OK, & the green mains ON LINE LED stays on & out goes the
             yellow ON BATTERY LED.

             If mains is just goes a bit to low the yellow SMART BOOST LED
             lights after a second of inverter fill in power.

             If the battery will not accept a charge the red REPLACE BATTERY
             LED is lit up.

Bargraphs:   The battery status bargraph indicates the battery voltage & is a
             good indication of the condition.

             The mains load bargraph lights up as the output loading is
             increased to the maximum 630W load. (100W/0.4A per LED)

Alarms:      The beeper sounds 4 beeps every 30 seconds after mains fails
             (1/30 seconds initial delay option SW3).

             And when the battery is too low (2min/5min warning) rapid pulse.

             And if the load is excessive.

Mains Fail:  As options set near instant changeover to synchronised inverter on
             failure, e.g. under/over volts, under/over frequency.

Mains Reset: After 5 seconds of good mains, near instant change back to mains.

Power off:   Just throw the rear ENABLE switch to off. This disconnects the
             output & stops all battery drain.
             Pressing the (0) button only works with no mains, otherwise you
             get a briefly interrupts the output only (dirty changeover).

Charging:    If just charging is needed then leave the rear ENABLE switch on
             without pressing (1) test button.

As with most things with uProc control that can go wrong & a full power off
with battery disconnection may be needed in the worst case. (e.g. before you
buy a new set of batteries!) Then do a fresh power up on recharged batteries
with a 30% mains load to recalibrate the uProc's battery predictions during the
self test.

MODIFICATIONS
As it will be used on a 24V Bus /P for broadcast/PA work where there may be
mains or not, I have done these modifications.

1/ Moved rear Enable switch to front of case
2/ Added 24V External battery point (externally fused @ 40A)
3/ Added "Mains In" neon to tell there is external power. (double insulated)
4/ Added "Power Out" neon to confirm output. (double insulated)
5/ Added "On" LED fed via 470R from 12V reg tab
6/ Added "Charging" LED, NPN base to charging R via 1k, & 330R to LED +12V
5/ Blackened internal heatsinks [runs a bit cooler on heavy loads (no fan)]
         ┌─┬─────────────┬─┐
   Eale│▒│:     °     :│ │
Mains In │o│: . . o . . :│¨│On LED
Power Out│o│~~~~~~~~~~~~~│¨│Charging LED
         │ │             │ │
         │ │  Operating  │ │
         │-│ - - - - - - │-│
         │ │Instructions │ │
         │ │             │ │
         │ │             │ │
         └─┴─────────────┴─┘

See my buls on "META HF Melenium 810 UPS", "Lead Acid Batteries", "Constant
Voltage Transforemers" & "Mains Power Protector".


Why don't U send an interesting bul?

73 De John, G8MNY @ GB7CIP



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