parkerVM600Mk2 A Second-Generation Architecture for a New Era

VM600 First-Generation:

One module does it all

When vibro-meter introduced 

the VM600 architecture in 2000, 

it represented a dramatic leap 

forward that sent shockwaves

through the industry with numerous

innovative features. 

The most notable of these was

the simplicity of an architecture 

that used a single card type – the 

MPC4 – to address all channel 

types except temperature. Prior 

architectures, and the prevailing 

model embraced by every other 

leading manufacturer of the time, 

was a reliance on a large diversity

of module types. For example, one 

well-known manufacturer required

more than 20 different module 

types in their system to achieve 

the full complement of all available 

functionality. 

Compounding the issue, each 

monitor module type had as many 

as 3 different corresponding I/O 

module variations. The spare 

parts implications were significant

– along with the widely varying

costs of each module depending 

on the channel types supported. 

It was a complex architecture with

a complex diversity of modules, a 

complex pricing structure, and a 

complex spare parts burden.

In contrast, the VM600 required

only 4 basic card types (power,

communications, temperature, and 

universally configurable vibration)

for comprehensive machinery 

protection, each with only a single

type of corresponding I/O module. 

In a word, the system was uniquely

simple – without sacrificing

functionality. It also introduced 

the concept of combining speed 

/ phase reference measurements 

on a single module as auxiliary 

channels. 

This allowed four channels of

vibration and two channels of

tachometer and/or phase reference 

to be addressed in a single rack

slot via the MPC4 (Machine 

Protection Card – 4 channel).

In fact, it perhaps would have been

better named “MPC4+2” for this 

very reason

. 

In addition, 4 relays were included

on each MPC4, turning a single 

module into a fully self-contained 

monitor with all required protective

functions. Hence, the slogan “one 

module does it all” aptly described 

the workhorse of the system: the

MPC4 module that provided true 

“universal” programmability for all 

required vibration channel types

and sensors.

The VM600 was introduced in

2000 and required only 4 basic

module types for comprehensive 

machinery protection functionality:

power, temperature, vibration, and

communications.

Segregated condition monitoring

Another key innovation of the

first-generation architecture was

entirely segregated, 16-channel 

condition monitoring (CM)

modules that ensured machinery 

protective functions could never 

be compromised by failures in the 

condition monitoring hardware,

yet resided in the same rack

chassis and could share input 

signals with the MPC4 protective

modules – or use entirely separate 

inputs if desired. Two CM module

types were available – one for

vibration (XMV16) and one for

gas turbine combustion dynamics 

(XMC16). Other manufacturer’s

platforms of the era used highly 

integrated condition monitoring 

that co-mingled protective and 

CM functions, resulting in a level 

of integration that amplified rather

than attenuated vulnerabilities.

The VM600’s first-generation

architecture physically separated 

condition monitoring from 

protection by using separate 

modules – the MPC4Mk1 for 

protection and the XMV16 for 

condition monitoring. A variant 

of the XMV16 (the XMC16) was

used for combustion dynamics 

monitoring on low-NOx gas

turbines.

As gas turbine firing temperatures

increased in the 70s, 80s, and 90s 

to achieve greater efficiencies,

these efficiencies came at the

expense of increased NOx

emissions. It was not long before

environmental concerns demanded 

these increased NOx emissions

be reduced, and new combustor

technology emerged as a result, 

referred to as Dry Low NOx

(DLN) or Dry Low Emissions (DLE)

designs1

.

Although these designs did indeed 

reduce NOx emissions, they

entailed so-called “metastable” 

combustion conditions that could 

impose extremely damaging 

dynamic pressure pulsation forces 

on the combustor2

. If not very 

carefully monitored and controlled, 

combustor life could be severely 

degraded.

It was out of this fundamental

need that gas turbine combustor 

monitoring emerged.

The concept is quite simple: adjust

the fuel/air mixture to be as lean 

as possible, but not so lean as 

to introduce an unstable flame

and the accompanying dynamic 

pressure pulsations that will

prematurely age (or destroy) the

combustor.

Using highly specialized hightemperature pressure sensors, the 

pressure inside each combustor 

is monitored for the presence of 

these damaging pulsations and the 

fuel/air ratio is continually adjusted

using a closed feedback loop

between the dynamic pressure

sensing system and the turbine 

control system where the fuel/air

mixture is adjusted.

When pulsations are detected, 

the flame is unstable and the