README3 - microMETER Polyphase Applications
- Re: Table 30a in README2
- Phase Selector Assembly
- Unavailable Neutral
- Diagrams
- Three-Phase Array of Single-Phase Processors (Legacy Technique)
- 480/277 Volt Service
- High-Leg Delta (mMII)
- Interactive Panel Schedule
- Network Feed (mMII)
- A 12-Story Building with 10 3-Phase 200-Amp 120/208Volt Services per Floor.
- Unbalanced Delta
- A Long Pier Having Boatslips with Buss-Fed Shore Power Pedestals
- A Mall Subdivided for Smaller Tenants
Page 1 Three-phase power is delivered in a variety of forms. The approach here is to utilize a non-Blondel solution (all non-neutral conductors measured independently) with a universal hookup. Any delta load can be viewed as an equivalent wye. Also, a wye without an accessible neutral can be treated the same way. A common service known as "high-leg delta" is handled a little differently in that it can be considered a 2-phase circuit (with two different voltages) requiring a PT suitable for each. Normally 3-phase measurement requires THREE PT's per processor connected through a Phase Selector Assembly. The general 3-phase hookup will look like this: A-phase PT \ B-phase PT ===Cat5=== Phase Selector Assembly ===Cat5=== mMII Processor C-phase PT / | Cat5 | Computer port
2 - Re: Table 30a in README2 - OLD way and NEW way (after July 2007)
Table 30b (External) Phase Selector Assembly (PSA) Connections (The NEW WAY after July 2007) ----Phase Selector Assembly----- Wire Colors Wire Colors Wire Colors Wire Colors *Terminal # (internal) to MMII to PT's to Computer 1 black dot orange (w white) orange (w white)
2 any (common) white w orange
3 white w brown brown (w white)
4 any (common) white w brown
5 brown (w white) green (w white)
6 any (common) white w green
7 orange (w white) orange (w white)
8 any (common) white w orange
9 any brown (w white)
10 any white w brown
11 green (w white) green (w white)
12 white w green white w green
13 blue (w white)
(This has nothing to do with it and
14 white w blue
just passes on to the computer.)
15 blue (w white)
16 white w blue
03/05/2008 NOTE: Each white-with-color wire should attach to an even-numbered terminal, e.g. 2, 4, 6, etc.
Pictorial:
PT120's
PT120's-to-PSA
PT's and RS232-to-PSA
PSA full
All with Type 2 Processor
*NOTE: The Terminal Board may have a second row of 16 terminals that is NOT USED at this time.
Be very careful to route the blue pair in from the processor and back out to the computer
without any crossing with other color pairs carrying 24 volts.
Table 30c - Using Cat5 for Extended CT or PT Clusters Wire Color Extended CT Clusters Extended PT Clusters 1 orange (w white)
A phase long A phase X2
2 white w orange A phase short A phase X1 (common)
3 brown (w white) B phase long B phase X2
4 white w brown B phase short B phase X1 (common)
5 green (w white) C phase long C phase X2
6 white w green C phase short C phase X1 (common)
7 blue (w white) spare spare
8 white w blue spare spare
Page 3
* Extreme care must be used to avoid confusing the Cat 5 connections.
The wires carrying 29 volts ac can make a nasty spark and damage
the main board. Reversal of R1 and R2 will cause voltage reference for B-phase
to be replaced with the voltage reference for A-phase. This could
remain undiscovered and affect accuracy of readings (based on AAC rather
than ABC).
In a 3-phase wye (with accessible neutral), true power, mMI or mMII applications the PT
primaries shall be wired as a wye with a connected neutral. (3/5/2008) The common point of
this neutral is the PSA terminals 2, 4, and 6. Reversing a PT secondary is fine if needed to
correct phase
BE SURE TO VERIFY THAT SECONDARY VOLTAGES
ARE BETWEEN 26 AND 32 VOLTS AC BEFORE CONNECTING TO PROCESSOR!
Use appropriate PT for phase-to-phase voltage.
1/30/2008 - Verify PT terminal phasing in parts list (Readme2) or by the connections used in the
desktop hookup. pic
PT pri
1 A-phase H1
2 B-phase H1
3 C-phase H1
4 H2 for A,B, and C
If polarity is not known, reversing PT secondaries on a trial-and-error basis is possible.
Absolute phase identification is not essential. The leftmost can be A, etc.
phase-to-phase voltage PT primary voltage
208 120
240 138.5*
416 240
480 277
*More than likely, this is a high-leg delta which only requires one PT120 and one PT208
The general 3-phase hookup will look like this:
A-phase PT \
B-phase PT ===Cat5=== Phase Selector Assembly ===Cat5=== mMII Processor
C-phase PT / |
Cat5
|
Computer port
A bank of three PT's may drive more than one processor extended according to Table 30c - Using Cat5 for Extended CT or PT Clusters (above). Allow 2va (PT power rating) for each processor phase and be very careful not to cross wires between processors
4 - Phase Selector Assembly
mMII connection to 3-phase PT secondaries shall use a Phase Selector Assembly. Table 31b - Phase Selection Channels: R1 R2 Processor toggles TP,AP (same as Powerstats Kit for mMI) 01 A ph TP,AP 0 0 02 B ph TP,AP 1 0 03 C ph TP,AP 1 1 04 A ph TP,AP 0 0 05 B ph TP,AP 1 0 06 C ph TP,AP 1 1 07 A ph TP,AP 0 0 08 B ph TP,AP 1 0 09 C ph TP,AP 1 1 10 A ph TP,AP 0 0 11 B ph TP,AP 1 0 12 C ph TP,AP 1 1 13 A ph TP,AP 0 0 14 B ph TP,AP 1 0 15 C ph TP,AP 1 1 16 A ph TP,AP 0 0 Phase sequence for a 120v wye can be determined this way. Identify the leading phase with the following tester: 60 watt bulb 60 watt bulb A ph ----0-------------|-------------0---- B ph | | | 15 watt fluorescent ballast coil (.75 henry) | | | neutral The leading phase will have the dim light and the lagging phase will have the bright one. *** 3-phase simulations 3-phase simulations Phase Selector Assembly tests w 120v wye High-Leg Delta test bed w 120/208/240 volts5 - Unavailable Neutral
In a 3-phase delta (or wye without accessible neutral) true power, mMI or mMII applications the PT primaries shall be wired as a wye with an isolated neutral. Stabilization of the PT neutral is necessary to remove 3rd-order harmonics. This may be done with tertiary set of windings connected as a closed delta. BE SURE TO VERIFY THAT SECONDARY VOLTAGES ARE BETWEEN 26 AND 32 VOLTS AC BEFORE CONNECTING TO PROCESSOR! Special PT's are needed. They must have two secondaries. The first secondaries must produce the required 29 volts each and are hooked in a wye (as before). The second secondaries can be any voltage (all three the same) and are hooked in a closed delta. All 60 hz voltages cancel in the delta and the harmonic currents flow inside the delta only. This can also be done with a second set of standard PT's connecting primaries in a wye and secondaries in a delta. Use this artificial neutral in the primary circuit to stabilise the floating neutral in the first set.6 - Diagrams
>>> 3-Phase Balanced Delta or Wye Load Measured on One Conductor With a Single-Phase Processor pic
Determine phase-to-phase voltage PPV. Enter voltage in SETUP as 1.7321 times PPV. e.g. 1.7321 * 208v = 360v. Enter in SETUP as actual CT size with voltage determined above. 1/25/2008 - This is to show 3x power usage for one phase and 1x ampere demand. >>> 3-Phase Unbalanced Delta or Wye Load Measured on Three Conductors With a Three-Phase Processor pic
6.3 - Three-Phase Array of Single-Phase Processors (Legacy Technique)
The original method for measuring multiple 3-phase loads with Type 1 (mMI) processors is to use sets of three with one dedicated to each phase. In some cases this would still be a little cheaper with the Type 2 (mMII) processor without using the Phase Selector Assembly. This would allow three 16-channel processors to meter 16 3-phase loads. The 16th channel is not wasted and less hardware is required (no Phase Selector Assembly). The downside is that information about any given 3-phase circuit resides on 3 separate processors and must be combined upon readout.6.5 - 480/277 Volt Service
The initial UL listing for this product permits use in this higher voltage environment with the condition that all CT leads have 600-volt insulation and individually bear a marking "600v". Up to this point, compliance has been addressed by using an orange
colored wire of this rating
for all CT's regardless of their ampere rating.
The ampere rating for the under 300-volt applications uses lead color to distinguish ampere rating
according to the following color code:
For up to 300 volts:
p/n
CT20 20 blue 
CT40 40 green 
CT60 60 yellow 
CT100 100 white 
This color-code is followed on the high-voltage CT's by another means such as a colored sticker
applied to each CT, or colored shrinkwrap/nylon ties spplied to leads.
They are designated with HV appended to the part number, e.g. CT20HV.
Depending on the layout of a switchgear room, it may be desirable to transition from the thick orange wire to
Cat5 or similar color-coded wiring after the thick orange wire has left the 480-volt enclosure. Use the
Table 30c - Using Cat5 for Extended CT or PT Clusters (above) as a color assignment guide. Use of exposed
terminal barrier strips presents no hazard because the microMETER-supplied CT signals are in the millivolt range.
It is not necessary to de-energized metered circuits to service these connections.
7 - High-Leg Delta (mMII)
This is a most common service for a small one-customer commercial location. A single- phase 120/240 volt service is augmented with a 208 volt leg from an open delta (2 pot) or full delta (3 pot) utility drop. The 120/240 feeds standard fixtures and appliances and the 208v feeds lighting at a 90-degree phase shift. Proper phasing for an analytical installation is difficult to plan but easy to remedy. Phase rotation and identification is not necessary with this procedure. Install as for single-phase using a PT120 and reserving every 3rd channel (3,6,9,12, and 15) for 208v loads. The PT120 will feed A phase and B phase (reversed) per Table 30a. Ensure that true power reads correctly on the single-phase channels (1,2, 4,5, etc.) reversing any incorrect CT connections. If more than half are wrong, reverse the PT120 X1,X2 connections first and check it again. Now connect the PT208 to C phase (per Table 30a) and check every 3rd channel. If more than half are wrong, reverse the PT208 X1,X2 connections. Reverse any remaining CT connections that are incorrect on the 208 volt circuits. High-Leg Delta
8 - Network Feed (mMII)
02/28/2008 - Not recommended. Use 3-Phase PSA or Three-Phase Array of Single-Phase Processors (Legacy Technique).
For situations where two of three phases (assume A and B) are supplying 120/208-volt service, alternating odd/even channels may be used to select either of the two phases. MUX16 address low-order bit is on line A0 (on pin 17 in the MUX16 Dual Inline Package). This is brought out to a pad, coincidentally next to, and tied to, pin 17 of the microprocessor. Modify the board by installing a 1K 1/8 watt resistor from this pad to the emitter of Q1 (labled R1 for phase selection) and clip the 1K resistor currently driving it. See the red trace below. Put the resistor at the pad, clipped and laid flat with 4" #24 solid running to R2 around the MUX16 and under the decoupling cap along the way. Use the phase selector as in a 3-phase installation with B-phase PT driving B-phase and C-phase input and the R2 control line unconnected. Channel assignments will alternate with 1,3,5, ... assigned to A-phase and 2,4,6, ... assigned to the B-phase.
Network Power Treated as Single-Phase
9 - A 12-Story Building with 10 3-Phase 200-Amp 120/208Volt Services per Floor. (in progress)
Based on an actual installation, a mixed-use (commercial/residential) facility is submetered for up to 120 users. The building has an east side electrical room and west side electrical room on each of the 12 floors. Crosswiring from east to west was inconvenient so all Cat5 wiring is vertical only and converges on the 1st floor. A Type 2 processor is required in each electrical room (east and west, 12 floors) for a total of 24. Potential Transformers (PT's): 02/28/2008 - Be sure to provide a local disconnect switch (3pdt @1A) for the PSA feed. PT BANK 1: Three 24-volt, class 2 PT's are installed on the 1st floor to serve the first 8 (of 24) processors on floors 1 thru 4. Three contractor outlets are provided for each primary phase A, B, and C, spaced to allow transformers to be plugged in side-by-side. The secondaries are bussed per Table 30c (Using Cat5 for Extended CT or PT Clusters) up through the east and the west chases. East and west circuits are paralled to the same secondaries. A 20 va PT can supply 10 processor-phase loads. The phase selector assembly for each processor can tap and propagate this Cat5 bus up to each succeeding floor. PT BANK 2: Installed on 1st floor using same primary feed as PT BANK 1. Paralleled secondaries for east and west will be available on floors 5 thru 8. PT BANK 3: Installed on 1st floor using same primary feed as PT BANK 1. Paralleled secondaries for east and west will be available on floors 9 thru 12. First Floor Retail Area: The bakery panel is currently in service and is likely to be the most complex. The schedule is: 40 double (A,B) 20 single (C) 150 triple (107) 150 triple (103) 150 triple (105) 150 triple (106) 200 triple (101) 150 triple (101) The 40/20 can be either ignored or wires could be routed through CT's used on one of the triple breakers. The processor will be mounted next to the panel to facilitate CT lead routing. The breakers on the processor side will need less CT lead length than those opposite. The bakery (101) has two breakers that must be metered together as one. The 000 wires are too far apart to share one set of 3 CT's. Instead, six CT's will be used and their signals will be added in series (long lead of one to short lead of other) and wires dressed again as a long and short pair. 18 CT's will be used in this panel. Channel Assignments: 1 107 A 2 107 B 3 107 C 4 105 A 5 105 B 6 105 C 7 101 A + A 8 101 B + B 9 101 C + C 10 103 A 11 103 B 12 103 C 13 106 A 14 106 B 15 106 C 16 not used - jumpered The corresponding CT.DAT file looks like this: 1 - 107 A ,0200,1.00,120,000,999 . 2 - 107 B ,0200,1.00,120,000,999 . 3 - 107 C ,0200,1.00,120,000,999 . 4 - 105 A ,0200,1.00,120,000,999 . 5 - 105 B ,0200,1.00,120,000,999 . 6 - 105 C ,0200,1.00,120,000,999 . 7 - 101 A + A ,0200,1.00,120,000,999 . 8 - 101 B + B ,0200,1.00,120,000,999 . 9 - 101 C + C ,0200,1.00,120,000,999 . 10 - 103 A ,0200,1.00,120,000,999 . 11 - 103 B ,0200,1.00,120,000,999 . 12 - 103 C ,0200,1.00,120,000,999 . 13 - 106 A ,0200,1.00,120,000,999 . 14 - 106 B ,0200,1.00,120,000,999 . 15 - 106 C ,0200,1.00,120,000,999 . 16 - ,0000,1.00,120,000,999 . Physical Mounting:
Refer to: Table 30b (External Phase Selector Assembly Connections The NEW WAY) above
10 - Unbalanced Delta
11/06/07 A motel has a/c units wired in groups of three as sides of a 208-volt delta fed from 3-pole breakers. It is desired to meter them from the panel and separate them out. Gut feel plus a bit of research saya this cannot be done. The measurement of individual phase power for unbalanced three phase delta loads requires that the individual phase voltage and current be accessible. Because delta power offers only phase voltage and line current, the required phase current is typically not available. An exception is the case where the load is made up of three sets of single phase loads and both conductors for each single-phase load are accessible. In the more typical situation where only phase voltage and line current are available, the determination of phase current given the line current is mathematically not possible due to unknown contributions of phase currents that form the resulting line currents. Moreover, in an unbalanced system the individual phases are not necessarily at a predetermined magnitude and phase relationship with each other thereby making presumptions based on incomplete information likely to be inaccurate. Example: Two of 3 units operate for an hour. Equal current is drawn on the two phases that feed the unit that did not run. How can that be distinguished from that (off) unit actually running? Solution: It will be necessary to place a CT remotely on each unit that measures current through that unit only. For true power measurement to be accurate, a 3-phase processor must be used with PT primaries arranged in a delta. A simpler approach would be to measure apparent power and adjust with a constant power factor in the software setup.
11 - A Long Pier Having Boatslips with Buss-Fed Shore Power Pedestals
12/12/07 First, determine that these circuits are NOT individually wired back to a distribution panel. Such an installation would be much simpler if made at the panel itself. When the pedestals are buss-fed, we must pick up the individual power consumption at each one. A twisted pair telephone-style connection is required for each. These may be already in place as unused telephony circuits. If they must be provided, the best approach is to use shielded Cat 5 cabling that is protected from salt spray and electrostatic discharge (lightning) to reach groups of 4 pedestals. Begin with the farthest slips at the end of the pier. A run of Cat 5 is pulled to the farthest pedestal and the first pair (orange) is attached per Table 30c - Using Cat5 for Extended CT or PT Clusters (above). At the next-most-remote pedestal, the Cat 5 is looped into the enclosure and peeled to obtain the second pair (brown). This is repeated for the green and blue pairs. The cable end and its color-pair assignments must be carefully marked and documented. Protective conduit can be slipped over wires and cut to size as this is done for each pedestal. Alternatively, wires may be bundled and supported under a rail or ledge.
12 - A Mall Subdivided for Smaller Tenants
01/18/2010
END OF DOCUMENT README3
