Meggitt vibro-meter VM600 - Dual Mathematical Function

HARDWARE MANUAL Document reference MAMPS-HW/E
VM600 machinery protection system (MPS) Edition 18 - March 2022
7-30
Dual mathematical function
PROCESSING MODES AND APPLICATIONS
7.17Dual mathematical function
(1) Description
Dual mathematical function (DMF) processing provides a range of dual-channel
mathematical functions that operate on the single-channel processed outputs of the
measurement channel inputs on an MPC4 card (see Figure 7-28).
The mathematical functions provided include basic mathematical operations (addition and
subtraction) and discriminator operations that select the minimum value or the maximum
value from the two input channels.
NOTE: DMF processing only operates on the first processed outputs from the
single-channel processings (shown as Out 1 in Figure 7-28).
The mathematical functions are:
• RMS Sum which performs the RMS addition of two single-processing input channels:
( (Channel 1)
2
+ (Channel 2)
2
)
0.5
or ( (Channel 3)
2
+ (Channel 4)
2
)
0.5
The RMS Sum function requires that both input channels are configured with an RMS
rectifier.
• RMS Subtraction which performs the RMS subtraction of two single-processing input
channels: ( (Channel 1)
2
− (Channel 2)
2
)
0.5
or ( (Channel 3)
2
− (Channel 4)
2
)
0.5
The RMS Subtraction function requires that both input channels are configured with an
RMS rectifier.
NOTE: For RMS Subtraction, if (Channel 2)
2
> (Channel 1)
2
or
(Channel 4)
2
> (Channel 3)
2
then zero (0.0) is returned.
• SUM which performs the addition of two single-processing input channels:
(Channel 1 + Channel 2) or (Channel 3 + Channel 4)
The SUM function requires that both input channels are configured with the same
rectifier.
• SUBTRACTION which performs the subtraction of two single-processing input channels:
(Channel 1 − Channel 2) or (Channel 3 − Channel 4)
The SUBTRACTION function requires that both input channels are configured with the
same rectifier.
• X & Y MIN which selects the smaller value from two single-processing input channels:
Minimum { (Channel 1 , Channel 2) } or Minimum { (Channel 3 , Channel 4) }
The X & Y MIN function requires that both input channels are configured with the same
rectifier.
• X & Y MAX which selects the larger value from two single-processing input channels:
Maximum { (Channel 1 , Channel 2) } or Maximum { (Channel 3 , Channel 4) }
The X & Y MAX function requires that both input channels are configured with the same
rectifier.
NOTE: In order to use dual mathematical function (DMF) processing with two
single-processing input channels, both single-processing input channels
(channel 1 and channel 2, or channel 3 and channel 4) must be configured with the
same single-channel processing function (for example, broad-band absolute
bearing vibration (BBAB)) and with rectifiers from the same rectifier group (for
example, AVG, RMS or True).