Specifications

98AEtypSMSspec_RevC.doc

SP-0012 Rev. C 09/05/09

J. Inverter Overload Protection

The inverter output shall utilize the electronic inverter current limiting for protection

against overload conditions (excessive overload, faults). The inverter shall utilize a

contactor to isolate its output from the critical bus and the load transferred to the bypass

source. The bypass static switch circuit shall be sized to provide fault clearing. The

inverter output isolation contactor shall be located internal to the UPS module and shall

be controlled by the internal UPS Module control.

The DC input to the Inverter shall utilize fuses for overload protection. Inverter fuses

shall be fast acting semiconductor type to clear faults on the DC link.

K. Inverter Output Isolate

The inverter output contactor isolates the inverter from the load and bypass source.

L. Line Drop Compensation

The inverter shall be provided with circuitry such that its output voltage rises linearly with

output current. The rise shall be required to achieve this function, and it shall not

interfere with other requirements of this specification. The purpose of this feature is to

compensate for varying line drop voltage between the inverter and the critical load

M. Inverter Operation Inhibit

The external dry contact can inhibit the inverter operation. When UPS condition is load

on inverter, load is transferred to bypass.

2.2.3 UPS Module Control and Monitoring

A. UPS Module Control and Monitoring operates and controls the hybrid converter, inverter

and independent automatic bypass static switch circuit

B. The UPS Module control circuitry utilizes Digital Signal Processor (DSP) and Application

Specified IC (ASIC) which create advanced controllability and simplify the control circuit.

Direct Digital Control (DDC) utilizing DSP and ASIC ensures high reliability, as well as

superior functionality and performance.

C. The UPS Module utilizes unique Major and Minor Feed Forward Current Loop Control,

enabling instantaneous control of UPS Module output. The digitalized UPS Module

incorporates Field Programmable Gate Array (FPGA) for Current Minor Loop Control,

and DSP based control for Feed Forward Control and Voltage Major Loop Control. DSP

Sampling Frequency is 30kHz, therefore the control samples 500 times in 1 cycle of

output voltage. Output voltage can therefore be controlled with high precision.

D. The UPS Module inverter utilizes solid state PWM controlled IGBT power transistors,

with the adoption of a unique Mitsubishi Electric Modulation method, enabling improved

switching frequency (for efficiency improvement) and high-speed response.

E. All UPS Module Control and Monitoring printed circuit boards shall be hermetically

sealed to protect against corrosive vapors.