Specifications

98AEtypMMSspec_RevB.doc

SP-0011 Rev. B 9/5/09

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.

2.2.4. 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

(working in conjunction with UPS MMS Control).

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.

F. The UPS Module Control power supply employs a redundant design

configuration, utilizing the UPS AC input (utility), Bypass input and the UPS

Module inverter output therefore enhancing reliability.

2.2.5. Bypass and Static Switch

A. Each UPS Module contains an independent automatic bypass static switch

circuit and associated bypass static switch transfer control circuitry (UPS

Module Control and UPS MMS Bypass Operation Control). Refer to the

previous section UPS MMS Bypass Operation. The bypass circuit shall be the

alternate source of power to the critical load other than by inverter supply. The

static switch shall be a high speed transfer device comprised of naturally

commutated SCR’s. The static switch and a wrap around contactor shall be

used to feed the critical load during automatic or manual transfers to the UPS

Module bypass static switch circuit.

B. The wrap around contactor shall be electrically connected in parallel to the