UPSB220 Uninterruptible Power Supply Caterpillar

Illustration 1	g02361044
Control Panel (1) Rectifier/charger light (2) Battery light (3) Static-bypass light (4) Inverter light (5) Load light (6) Buzzer (7) Inverter ON button (8) Inverter OFF button (9) Scroll Up/Increment key (10) Scroll Down/Decrement key (11) Validate key (12) Main Menu key (13) Voltage Measurement key (14) Current Measurement key (15) Frequence and Power Measurement key (16) Anomaly light (17) Primary Message Key (18) Battery Key (19) Forced-transfer (20) Alarm reset (21) Buzzer reset (22) Display

Illustration 2	g02345901
Circuit Breaker Diagram The fuses are to protect against catastrophic rectifier and inverter semiconductor failure that could be caused by the normal AC source or the load.

Normal AC input (30) - Three-phase 480 VAC 60 Hz line voltage. Utilized in Normal operation to support the load.

Bypass AC input (31) - Three-phase 480VAC 60Hz line voltage utilized in Bypass or Maintenance operations to support the load.

Q1 (32) - Isolates the rectifier/charger (A) from the normal AC source (30). Q1 is a molded circuit breaker.

Rectifier/charger module (A) - Converts three-phase AC power from the normal AC source supply (30) into DC power for the normal inverter (B) input. This module float charges or recharges the battery (D) .

Inverter module (B) - Converts the DC power supplied by the rectifier/charger module (A) or the battery unit (D) into three-phase AC power for the load.

Q5N (33) - Q5N is a switch that can isolate the UPS system from the load.

QF1 (34) - QF1 is a circuit breaker for battery (D) protection and isolation.

Battery unit (D) - The battery unit provides backup power for the inverter (B) in the event of a voltage drop or a normal AC input (20) failure.

Static bypass module (C) - Ensures the instantaneous transfer of the load to the bypass AC source input (31) in the event of an inverter (B) shutdown. The shutdown can be initiated by the user, by a protective device, or a sudden load.

Q4S (36) - Q4S is a switch that isolates the static bypass (C) from the bypass AC source input (31) .

Q3BP (35) - Q3BP is a switch to isolate the UPS for maintenance. During maintenance the Q3BP transfers the load to the bypass AC source input (31) without interrupting the supply of power.

Note: The normal AC input and the bypass AC input have different functions. Depending in the installation, each input may be protected differently upstream and/or come from different sources.

Normal Mode

Normal AC source power is available. Refer to Illustrations 1 and 2.

The following green lights on the control panel are ON:

• (1) Rectifier/charger light

• (4) Inverter light

• (5) Load light

The power necessary for the load is provided by the normal AC source (30) through the rectifier/charger (A) and the inverter (B) .The rectifier/charger (A) also supplies the power to float charge and recharge the battery if any

The DC output voltage is regulated to supply the following conditions:

• The float-charging or the recharging voltage for vented lead-acid or Ni/Cd batteries

• A single charge voltage for sealed lead-acid batteries

The voltages depend on the number of battery cells and the battery manufacturer. The voltages are factory set, however the voltages may be adjusted by support technicians.

An electronic board continuously measures the battery temperature and automatically adjusts the voltages

In parallel UPS systems, the power drawn by the load is equally shared between the different units.

Operation With The Normal AC Source Down

Refer to Illustrations 1 and 2.

In the event of a normal AC source failure or voltage outside specified tolerances of ±10% in amplitude (±15% optionally), the rectifier/charger (A) stops and the battery (D) supplies the necessary backup power to the load via the inverter (B). The battery, float-connected between the rectifier/charger and the inverter, discharges during this operating mode:

• (2) Battery light on the control panel is ON green

• (4) Inverter light on the control panel is ON green

• (5) Load light on the control panel is ON green

The user is warned of battery operation by the slow beeping of the buzzer (6). The message "LOAD PROTECTED, BATTERY DISCHARGING", followed by the remaining backup time and the percent load is shown on the display (22). This information is also available via volt-free changeover contacts for remote control devices.

Operation With The Normal AC Source Restored

Refer to Illustrations 1 and 2.

When normal AC source power (1) is restored or the normal AC source power voltage returns to within specified tolerances, the system automatically returns to normal operating mode. Refer to "Normal Mode".

Note: Normal operating mode is restored providing the unit did not reach the end of battery power.

If the end of battery power was reached, prompting an inverter shutdown, the rectifier/charger (A) restarts automatically, but the inverter (B) must be restarted manually.

The rectifier/charger recharges the battery (D) which was discharged during the source power outage. During battery charging, light (2) flashes green.

The message "BATTERY CHARGING" is shown on the display (22) together with the value of the recharging current and battery voltage.

Illustration 3	g02364077
Battery charge cycle chart

The battery charge cycle takes place in two steps:

• The battery is recharged at a constant current limited to 0.1C10 (1/10th of the battery capacity specified for a 10 hour discharge). The DC voltage increases with the battery charge until the charge level is reached.

• The battery is recharged at constant voltage equal to the charge level. The charging current gradually decreases until reaching a specified low value (floating current).

For vented lead-acid batteries, the rectifier/charger supplies the charging voltage for 0 to 255 hours then the floating voltage. A parameter is defined by the after-sales support department. For sealed lead-acid batteries, the charging and floating voltages are the same.

Note: If the normal AC source failure is shorter than 0 to 255 seconds the charger automatically supplies the floating voltage given the low battery discharge. The default value is 30 seconds and this value is defined by the after sales support department.

Operation With Engine Generator Set

Illustration 4	g02364176
Installation with an Engine Generator Set

If a stand-by generator is included in the installation, the generator is started automatically in the event of a normal AC source failure and connected to the main low voltage switchboard. The stand-by generator is disconnected when normal AC source power is restored.

Refer to Illustrations 1 and 2.

With such a system, the required battery time may be reduced to the time necessary for starting and bringing the stand-by generator on line. The battery (D) supplies power to the inverter (B) during the transfers conditions listed below:

• Normal AC source to the generator

• Generator to the normal AC source

The transfer sequences described above are fully automatic. The transfer sequences do not affect the load and require no manual operation by the user.

Note: To avoid load surges on the generator, the rectifier/charger (A) is started with a 10 second maximum current consumption walk-in that lasts 3 to 10 seconds, depending on the percent load.

Note: To avoid overloading an undersized engine generator set, you may set a maximum power level drawn by the normal AC input. Any additional power required is supplied by the battery. This modification must be made on site by an authorized Caterpillar dealer.

Battery Time

The available battery time during a normal AC source outage depends on the conditions:

• Rated capacity of the battery

• Power consumed by the load

• Temperature of the battery

• Age of the battery

The specified battery time corresponds to a minimum duration at full rated load. The actual backup time may be greater if the system operates below the full rated load during the normal AC source outage. Operation on battery power can be extended beyond the specified time by reducing the load power consumption (by disconnecting non-critical loads).

A "low battery" warning signal is sent via volt-free changeover contacts for remote control devices when the battery voltage reaches a level slightly above the minimum level. This signal warns the user of the imminent end of battery power. The buzzer (6) beeps rapidly on the device.

The message "LOW-BATTERY SHUTDOWN WARNING" is shown on the display (22), followed by the remaining backup time and the percent load. Battery light (2) turns red and flashes.

Battery power stops when the voltage supplied by the battery reaches the minimum threshold. This condition results in inverter shutdown and transfer of the load without interruption to the bypass AC source. Battery light (2) shines steady red. The message "LOAD NOT PROTECTED, ON-LINE MODE" is shown on the display (22) and the buzzer (6) sounds continuously.

If the bypass AC source also fails, the load is no longer supplied. The inverter automatically shuts down when the time on battery power exceeds three times the specified backup time.

Note: The "Low Battery Shutdown" warning signal can be sent with an adjustable time delay prior to the effective end of battery power.

Inverter Shutdown Or Overload

Devices or installations operating in on-line mode with a Bypass AC source.

Illustration 5	g02380458
Operating in On-line Mode Diagram

Single UPS Unit (On-Line Mode)

Illustration 6	g02381120
Overload Curve Diagram

In the event of a UPS shutdown that is initiated by the user or by an internal protective device, the load is automatically transferred to the bypass AC source. If transfer conditions are satisfied, transfer takes place instantly without interruption to the load.

Note: Transfer conditions are not satisfied when the bypass AC source characteristics are outside of the tolerances listed below:

• Voltage ±10%

• Frequency as per personalization

• Phase sync with inverter ±3°

In the event of a major transient overload that is greater than 1.65 In, immediate transfer takes place as above, without interruption to the load.

The number of possible returns to the inverter is 0 to 255, programmable by personalization. The return to the inverter is automatic when the overload disappears if the number of possible returns has not been reached. If this number has been reached, the load continues to be supplied by the bypass AC source. This operating mode allows start-up of load devices causing high inrush currents.

This system requires satisfied transfer conditions. If the conditions are not satisfied, the inverter will current limit to 165% of the rated current for 1 second before stopping.

In the event of a small but extended overload such as a continuous level of power exceeding the full rated load, the inverter will continue to supply power for a period of time depending on the magnitude of the overload as described below:

• 10 minutes for a 125% overload

• 1 minute for a 150% overload

Refer to the overload curve in Illustration 6.

In all the above cases, inverter shutdown and supply of the load via the bypass AC source results in the following actions on the control panel:

• Inverter light (4) goes off

• Buzzer (6) is activated and sounds continuously

• Static-bypass light (3) goes on and turns green

• The message "LOAD NOT PROTECTED, ON-LINE MODE" is shown on the display (22)

Parallel UPS Without Redundancy

The shutdown of one inverter results in overload on the other inverters in operation. The two cases listed below may then arise:

• If the overload on each remaining inverter is > than 1.65 in, the load is immediately transferred to the bypass AC source.

• If the overload is < 1.65 in, the remaining inverters support the overload and the load is transferred to the bypass AC source

Refer to the overload curve in Illustration 6.

After this transfer the following actions occur on the control panel:

• Inverter light (4) goes off

• Buzzer (6) is activated and sounds continuously

• Static-bypass light (3) goes on and turns green

• The message "LOAD NOT PROTECTED, PARALLEL ON-LINE MODE" is shown on the display (22)

Parallel UPS With Redundancy

The shutdown of one UPS unit is of no consequence for the load. The other UPS units each take up an equal amount of load power and the load continues to be supplied normally.

Unit shutdown results in the following actions on the control panel:

• Inverter light (4) goes off

• Load light (5) goes off

• Buzzer (6) is activated and sounds continuously

• The message "LOAD NOT PROTECTED, PARALLEL ON-LINE MODE" is shown on the display (22)

In the event of an overload, the system only loses redundancy as long as the overload is less than the total rated power of the functioning units. If the overload is greater, the operating mode is that previously described for systems without redundancy.

Output Voltage Quality And Continuity

The output voltage is stable in amplitude and frequency, is free of interruptions or transients outside specified tolerances, irrespective of normal AC source or load disturbances such as outages load step changes.

Steady State Voltage Regulation

For stable or slowly varying load conditions, the inverter output voltage is regulated to within ±5% in amplitude.

The frequency of the output voltage can theoretically be regulated to within 1% of the rated value, however the output frequency range may be intentionally extended to a maximum of ±2 Hz so that the inverter can remain synchronized with the bypass AC source and inherent frequency fluctuations, thus enabling transfer of the load to the bypass line at any time.

When the bypass AC source frequency returns to within the specified tolerances, the inverter is gradually resynchronized to the bypass line at a rate of 5 Hz to 2 Hz. These values are set per the values personalized by an authorized Caterpillar dealer, thus avoiding exposing the load to sudden frequency variations.

Transient Voltage Regulation

The inverter output voltage is not notably affected by instantaneous major variations in load characteristics.

This condition is made possible by the Pulse Width Modulation (PWM) chopping technique and the microprocessor-based regulation system that instantly compensates for any variation. In particular, the inverter output voltage remains within ±2% of the rated voltage for load step changes of 0 to 100% or of 100 to 0%.

The battery charge cycle takes place in two steps.

1. The battery is recharged at a constant current limited to 0.1C10 (1/10th of the battery capacity specified for a 10 hour discharge). The DC voltage increases with the battery charge until the charge level is reached.

2. The battery is recharged at constant voltage equal to the charge level. The charging current gradually decreases until reaching a specified low value (floating current).

For vented lead-acid batteries, the rectifier/charger supplies the charging voltage for 0 to 255 hours (parameter is defined by an authorized Caterpillar dealer) then the floating voltage.

For sealed lead-acid batteries, the charging and floating voltages are the same.