The following reference topics provide detailed technical information on the Premium Monitoring System capabilities and legal information.
|
Monitored Line |
Scan Rate in Monitoring Mode |
Scan Rate for 6-Hour Snapshots |
Attenuation Ratio |
|---|---|---|---|
|
Ground current |
1 MS/second |
20 MS/second |
50 A : 10 V |
|
Shaft voltage |
1 MS/second |
20 MS/second |
100 V : 10 V |
|
Shaft metering rope wear indicator |
100 kS/second |
100 kS/second |
100 V : 10 V |
|
Ground rope wear indicator |
100 kS/second |
100 kS/second |
100 V : 10 V |
When live, hourly, and daily values trend outside the norm of the longer-term averages. This indicates that changes are taking place in the generator’s operation. Changes in trending values may be an indicator to manually record and download a new set of waveform snapshots for comparison against past waveforms collected. The information and ratios revealed in these waveforms can potentially assist in identifying the root cause of the change and can be used by trained individuals to identify potentially significant changes taking place in the generator’s bearings, windings, insulation, or other key components.
-
Average voltages and currents are calculated on the samples taken during each snapshot as the sum of (x)/N, where x is the array of samples acquired, and N is the number of samples.
-
Zero-to-peak voltages and currents are calculated on the samples taken during each 0.02 second snapshot by the following formula:
max(x) - min(x)
-
The longer-term averages are calculated by accumulating averages for the specified period. They are then reset in preparation for the next calculation. The formula used is as follows:
NewAverage
=
( PreviousSampleCount x PreviousAverage ) + SnapshotAverage ___________________________________________________________
PreviousSampleCount + 1
The 4–20 mA output connection points are located inside the Premium Monitoring System, on the right side of the box, and they are designated by the white and black twisted-pairs. The terminal strips are labeled to indicate which signal pair is carried at each terminal connection point. If the label is missing, refer to the following table to identity the connection points from left to right.
For EZDP-2038:
For EZDP-2020:
Table 1. 4–20 mA Output Connection Points
|
Shaft V RMS Avg |
Shaft V O-P |
Gnd I RMS Avg |
Gnd I O-P |
Rope Status |
Alert LED |
||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
White |
Black |
White |
Black |
White |
Black |
White |
Black |
White |
Black |
White |
Black |
|
- |
+ |
- |
+ |
- |
+ |
- |
+ |
- |
+ |
- |
+ |
The 4-20 mA outputs are intended to be used with a plant DCS. Refer to the following four tables when programming.
Table 2. Shaft Voltage Average Output Values
|
Shaft Voltage (V) |
Conditioned Voltage (V) |
4-20 mA Output |
|---|---|---|
|
-100 |
-10 |
4 |
|
-50 |
-5 |
8 |
|
0 |
0 |
12 |
|
50 |
5 |
16 |
|
100 |
10 |
20 |
Table 3. Shaft Voltage Zero-to-Peak Output Values
|
Zero-to-Peak Voltage (V) |
Conditioned Voltage (V) |
4-20 mA Output |
|---|---|---|
|
0 |
0 |
4 |
|
25 |
2.5 |
8 |
|
50 |
5 |
12 |
|
75 |
7.5 |
16 |
|
100 |
10 |
20 |
Table 4. Ground Current Average Output Values
|
Ground Current (A) |
Conditioned Voltage (V) |
4-20 mA Output |
|---|---|---|
|
-50 |
-10 |
4 |
|
-25 |
-5 |
8 |
|
0 |
0 |
12 |
|
25 |
5 |
16 |
|
50 |
10 |
20 |
Table 5. Ground Current Zero-to-Peak Output Values
|
Zero-to-Peak Current (A) |
Conditioned Voltage (V) |
4-20 mA Output |
|---|---|---|
|
0 |
0 |
4 |
|
12.5 |
1.25 |
8 |
|
25 |
2.5 |
12 |
|
37.5 |
3.75 |
16 |
|
50 |
5 |
20 |
For EZDP-2038:
For EZDP-2020:
If the external LED option is installed, any channel 6 output that is listed below as an alarm or warning causes the external LED indicator on channel 7 to flash until the condition is cleared.
Table 6. Channel 6—Rope and Unit Status
|
Range Low |
mA Output |
Range High |
Condition |
Description or Recommended Action |
|
|---|---|---|---|---|---|
|
0 |
to |
3.9 |
Not a valid output level. |
4–20 mA line failure or monitoring powered off. |
|
|
3.9 |
4 |
4.5 |
Monitoring paused. Grounding current and shaft voltage both below minimal threshold. |
Alert: Generator offline. Not a fault. CMS paused. Monitoring resumes automatically when the generator resumes operation. This status should display only if the generator is offline. If the generator is online, notify Cutsforth of the error. |
|
|
4.5 |
5 |
5.5 |
Normal, generator online. |
Normal operation. No alarms indicated. |
|
|
NA |
#1 SGA Ground rope. |
#2 SGA Metering rope. |
6-12 mA: Rope status array. All else: Unit Status. |
||
|
5.5 |
6 |
6.5 |
#1 SGA Stepped up. |
#2 SGA Normal. |
Alarm # 1 fault. SGA ground rope. |
|
6.5 |
7 |
7.5 |
#1 SGA Normal. |
#2 SGA Stepped up. |
Alarm # 2 fault. SGA metering rope. |
|
8.5 |
9 |
9.5 |
#1 SGA Stepped up. |
#2 SGA Stepped up. |
Alarm #1 & #2: SGA ground and metering ropes. |
|
12.5 |
13 |
13.5 |
Storage reaching full capacity. |
Alarm: Download waveforms stored on the CMS. After confirming download was successful, delete the files on the CMS using the CMS File Manager. CMS will lock up if storage reaches full capacity. |
|
|
17.5 |
20 |
20.1 |
Grounding loss. Ground current (Below minimal threshold) and shaft voltage (stepped up). |
Warning. Probable loss of grounding. Urgent status. Inspect grounding hardware and confirm measurements at remote meter points. |
|
Channel 7 controls the external LED, when installed. Any of the following alarms, warnings, or status conditions raise the channel 7 output to 20 mA, which triggers a current-driven relay to supply 24 V DC power to the LED:
-
Rope fault
-
Operator-set threshold is crossed
-
Grounding lost
-
Storage full condition
-
If any LIVE values remain constant for a period of 10 seconds or longer, check the Premium Monitoring System for a possible frozen application or malfunctioning sensor. If the application reports an error, see Application Errors.
-
If the unit is online, but Channel 6 is transmitting 4 mA (indicating that generator is offline), check the Shaft Grounding Assembly for a loss of ground. For example, check the rope-to-shaft connection for any oil, dust, or other contaminants that may interfere with the electrical connection.
The length and size of the grounding cable are recommended based on the following plant-provided information:
-
The generator manufacturer’s recommendation for ground wire size
-
The manufacturer’s recommendation for shaft voltage and ground current alarm limits
-
The shaft voltages and ground currents as measured historically by the plant
-
Conduit run distance between the shaft grounding location (Shaft Grounding Assembly) and the Premium Monitoring System installation location
-
Conduit run distance between the Premium Monitoring System and the turbine case (ground)
A common installation will use 8 AWG wire, which carries 30 A DC at 12 V, assuming a maximum allowable voltage drop of 10% at 30°C (86°F).
-
30 amps x 60 ft = 1800 Famps (Feet x Amps). As shown in the following table, this puts the required wire size at 8 AWG.
-
30 A DC is approximately 10x what is commonly accepted as the DC threshold of a normally operating generator, so our wire size recommendation represents a safety factor of essentially 10x.
-
The 30 A DC minimum we have established also covers a single-phase AC load of 32 V on an 8 AWG wire over the same distance at a capacity of 80 A.
Note that ground current from turbine generators is most commonly not DC. More typically the ground current has a strong AC component. The AC component is commonly not a sine wave. Observed signals may have multiple momentary peaks implying that loads are quite large, but further examination reveals that the actual power load on the wire is remarkably less. For example, a specific generator we have under maintenance is showing a peak-to-peak ground current of 4.22 A. However, the average RMS ground current of that same time period is in actuality 0.12 A. So, if an engineer or technician is applying the typical RMS calculation of 0.35355 x "V PK-PK" to our reported value of 4.22 A, they would incorrectly assume that the RMS voltage is 1.49 when in reality this number in this circumstance is 12.43 times greater than the actual RMS ground current measured during the snapshot.
Table 7. Wire Size Characteristics
|
Wire Size |
Minimum Acceptable CM Area |
Wire Ampacity Nonengine |
Wire Ampacity Engine |
12 Volts Volt Drop |
24 Volts Volt Drop |
32 Volts Volt Drop |
||||
|---|---|---|---|---|---|---|---|---|---|---|
|
AWG |
Metric* |
3% Famps |
10% Famps |
3% Famps |
10% Famps |
3% Famps |
10% Famps |
|||
|
16 |
1 |
2336 |
25.0 |
21.3 |
86 |
288 |
173 |
576 |
230 |
768 |
|
14 |
2 |
3702 |
35.0 |
29.8 |
138 |
459 |
275 |
918 |
367 |
1223 |
|
12 |
3 |
5833 |
45.0 |
38.3 |
219 |
729 |
437 |
1458 |
583 |
1944 |
|
10 |
5 |
9343 |
60.0 |
51.0 |
348 |
1159 |
695 |
2317 |
927 |
3090 |
|
8 |
8 |
14810 |
80.0 |
68.0 |
553 |
1843 |
1106 |
3686 |
1474 |
4915 |
|
6 |
13 |
24538 |
120.0 |
102.0 |
879 |
2929 |
1757 |
5858 |
2343 |
7811 |
|
4 |
19 |
37360 |
160.0 |
136.0 |
1398 |
4659 |
2796 |
9319 |
3727 |
12425 |
|
2 |
32 |
62450 |
210.0 |
178.5 |
2222 |
7408 |
4445 |
14815 |
5926 |
19754 |
|
1 |
40 |
77790 |
245.0 |
208.3 |
2803 |
9342 |
5605 |
18684 |
7474 |
24912 |
|
0 |
50 |
98980 |
285.0 |
242.3 |
3536 |
11788 |
7073 |
23576 |
9430 |
31434 |
|
00 |
62 |
125100 |
330.0 |
280.5 |
4457 |
14858 |
8915 |
29715 |
11886 |
39620 |
|
000 |
81 |
158600 |
385.0 |
327.3 |
5619 |
18731 |
11239 |
37462 |
14985 |
49950 |
|
0000 |
103 |
205500 |
445.0 |
378.3 |
7086 |
23620 |
14172 |
47241 |
18896 |
62988 |
This chart assumes wire with 105°C (221°F) insulation rating and AWG wire sizes.
*Metric wire sizes may be used if of equivalent circular mil area.
Cutsforth recommends that signal runs be 40 ft (12 m) or less whenever possible. If longer runs are chosen, we do not guarantee what level of signal quality may be obtained. Longer runs have been functional for plants where tradeoffs were understood. Within reason, longer runs may provide the information needed to monitor basic grounding integrity and provide low-level waveform information.
The most important information that monitoring can supply is confirmation of the immediate status of the generator grounding. More advanced information includes waveform-level views of what is happening on the shaft and in the ground current, even at higher-frequency events. The signal quality that you experience is related in large part to cable length and site-specific interference. Model 88777 wire has a linear attenuation rate of 0.09 dB per foot when carrying a 10 MHz signal. The following levels of dampening are associated with each cable length:
-
30 ft (9 m): -2.7 dB (30 x .09)
-
50 ft (15 m): -4.5 dB (50 x .09)
-
75 ft (23 m): -6.75 dB (75 x .09)
Cutsforth considers attenuation exceeding 3 dB to be unacceptable.
The Belden wire spec sheet provides the following data on dB loss per ft @ the frequency stated:
-
0.1 MHz - 0.0040
-
0.5 MHz - 0.0190
-
1.0 MHz - 0.0300
-
2.5 MHz - 0.0457
-
5.0 MHz - 0.0700
-
10.0 MHz - 0.0900
Source: Belden data for Model 88777 at:
https://cutsforth.box.com/s/090z4vxegivh4ak7fruzac1qc1crl97k
These examples are based on distance attenuation of the cable only. In these examples, it is revealed that up to 500,000 samples per second will display reasonably relevant information at distances beyond 40 ft (12 m). However, a 10 MHz signal at 70 ft (21 m) will see a 50% to 60% dampening, not accounting for other factors. So at this distance a 10 MHz element in the waveform may not be discernible from noise.
For use in indoor and outdoor corrosive environments that require a water-tight seal, this enclosure’s seamless foam-in-place gasket and screw-down clamps provide a secure seal against contaminants.
14-gauge, Type 304 stainless steel bodies and doors. The mounting flanges of the enclosure are to be used with 3/8 in or M12 bolts. Final weight of the Premium Monitoring System assembly is 80 lbs.
Dimensions:
-
A—24.00 in (610 mm)
-
B—20.00 in (508 mm)
-
C—6.00 in (152 mm)
UL 508A Listed Type 4X File No. E61997 cUL Listed per CSA C22.2 No 94 Type 4X File No. E61997
NEMA/EEMAC Type 4X CSA File No. 42186: Type 4X IEC 60529 IP66
|
Plant-supplied power source |
120 V, 60 Hz AC |
|---|---|
|
Power source (optional) |
240 V, 50 Hz |
|
Circuit breaker |
Internal 120 V, 5 A |
|
Circuit draw under normal usage |
Approximately 0.6 A |
Please refer to the manufacturer’s datasheet:
Please refer to the manufacturer's datasheet:
Please refer to the manufacturer’s datasheet:
Please refer to the manufacturer’s datasheet:
This product is designed to meet the requirements of the following standards of safety for electrical equipment for measurement, control, and laboratory use:
-
IEC 61010-1, EN 61010-1
-
UL 61010-1, CSA 61010-1
This product meets the requirements of the following EMC standards for electrical equipment for measurement, control, and laboratory use:
|
EN 61326 (IEC 61326) |
Class A emissions; Basic immunity |
|---|---|
|
EN 55011 (CISPR 11) |
Group 1, Class A emissions |
|
AS/NZS CISPR 11 |
Group 1, Class A emissions |
|
FCC 47 CFR Part 15B |
Class A emissions |
|
ICES-001 |
Class A emissions |
|
CE Compliance |
Meets the essential requirements of applicable European Directives, as amended for CE marking, as follows: 2006/95/EC, Low-Voltage Directive (safety); 2004/108/EC, Electromagnetic Compatibility Directive (EMC) |
Please refer to the manufacturer’s datasheet:
-
The threshold and operator-initiated waveform files are accessible for download or deletion via the Premium Monitoring System Application’s File Manager.
-
Each event waveform snapshot recording is defaulted to 0.02 seconds long and captures 1.2 shaft rotations when the unit is operating at 3,600 RPM.
-
Each 6-hour waveform snapshot recording is defaulted to 0.02 seconds long and captures 1.2 shaft rotations when the unit is operating at 3,600 RPM.
-
Each 0.02 second snapshot is approximately 7.9 MB in size, but will vary depending on the user-set snapshot length.
-
Unit storage dedicated to event snapshots is just over 1 GB and accommodates approximately 120 snapshots before the Storage Low indicator lights up and the external LED flashes, if installed.
-
The system’s SD card storage is located in D:\Baseline Recordings. This folder is required for the Premium Monitoring System to operate and is dedicated to recording a snapshot every 6 hours for a total of four snapshots every 24-hour period that the generator is operational. 32 GB of storage is dedicated to the 6-hour snapshots and will accommodate between 2 and 3 years' worth of snapshots as measured in unit operating time.
|
Storage temperature |
-40 to +85°C (-40 to 185°F) |
|---|---|
|
Operating temperature |
-20 to 55°C (-4 to 131°F) |
|
Storage humidity |
10 to 95% RH, noncondensing |
|
Operating humidity |
20 to 90% RH, noncondensing |
|
Maximum altitude |
2,000 m (6,562 ft) |
The measurements below show overall system performance with the Premium Monitoring System completely assembled for the following lengths of signal cable of the type referenced in Cable Gauge, Length, and Signal Quality:
-
10 ft (3 m)
-
20 ft (6 m)
-
40 ft (12 m)
-
60 ft (18 m)
The graph below does not account for interference caused by the installed environment, but it does represent what can be expected when adding together the variables in the system’s signal acquisition chain. The shortest cable length possible is always our strongest recommendation.
The scope AC coupling cutoff takes place between 10 and 20 Hz depending somewhat on the length of cable installed. The response curve is fairly flat through the vast majority of the spectrum of expected signals that will take place on your generator. Amplification does ramp up slightly on signals occurring at approximately 100 kHz. At 300 to 500 kHz, deviation begins to appear most dramatically depending on cable length. Here it is evident that best overall signal acquisition is obtained by planning a SGA-to-Premium Monitoring System conduit length of 20 ft or less. At 40 ft, the plant needs to decide if they will tolerate the loss that takes place at the upper spectrum . The 60 ft signal cable is not recommended, showing a rapid drop off starting at around 4 MHz.
Note that the ground current and shaft voltage sensing equipment can capture events that typical hand-held voltage and amperage meters would likely miss. This may result in initial readings appearing higher than the plant is used to seeing depending on the measurement tools and methods used in the past. Also, like an oscilloscope with a long lead, even when the generator is offline it is likely you will see readings above 0 due to environmental noise and sensor noise.
-
Previous Version: v1.5.88
-
Code Addition: Code was re-written to enable the use of NI-9775 C-Series oscilloscope. Shaft monitoring and event snapshots are now monitored at a rate of 1 MS/s. six-hour snapshots are monitored at a rate of 20 MS/s.
-
Code Addition: Code was re-written to measure and report both DC and RMS values on the home page. Peak-to-peak voltage and current was changed to zero-to-peak. Highest peak was removed.
-
Code Addition: These threshold settings were added:
-
Pk Width: Time that voltage or current is sustained above the specified 0-Pk threshold setting.
-
Pk Period: Total length of time considered in the analysis.
-
Pk Count: Number of times the voltage or current needs to exceed the 0-Pk threshold and exceed the Pk Width within the Pk Period to be considered as a qualifying 0-Pk Alert Event.
-
-
Code Addition: “Event Snapshot Length” and “Six-Hour Snapshot Length” variable settings were added to the TECHNICIAN page. These values enable each plant to determine the length of the event and 6-hour snapshots within the limits of the system. The snapshot length setting does not change when Factory Reset is pressed.
-
Code Addition: Application error recovery functionality was added such that, in the event of an application error, the Cutsforth application will write an entry to the error log and reboot the monitoring system. The monitoring application will resume upon startup.
-
Firmware Update: A script has been developed by National Instruments that will check the National Instruments Measurement Automation Explorer (NI MAX) database upon startup for a configuration error which could lead to database corruption. Should the script find a configuration error, an entry will be written to an error log, the database configuration will be reset, and the monitoring system will be rebooted. Should the script find no configuration error, the Cutsforth monitoring application will be launched.
-
Bug Fixes: All bug fixes previously developed and included in Cutsforth application v1.5.88 are present in application v350.
-
Previous Version: 1.5.85.
-
Bug Fix: Remove code requesting second memory close request upon USB communication loss.
-
Code Addition: If for any reason USB communications are lost or corrupted, a soft reset of the scope will be initiated. If after 30 seconds reconnection of the scope is not successful, the system will represent the fault present as normal.
-
Code Addition: Added an Exit Application protection routine. In the event that anyone purposefully or inadvertently clicks the X to close the application, a confirmation window appears asking them to confirm the exit or continue monitoring.
-
Code Addition: Display Plant Name, Unit ID, and Date/Time to the header of each page of the application so it is present in photographs taken to assist with event and troubleshooting follow-up.