PRODUCT
“A2”
The “A2” load control governor is designed to manage loads and
govern frequency when used on independent small hydro plants
Without external relays, can be used on plants of size 1 KW to 12 KW,
240 volts (60 Hz), or 220 volts (50 Hz) single phase.
With external relays, can be used on plants of size 1 KW to 114 KW, 240
volts (60 Hz) or 220 volts (50 Hz) single phases, 208/240 volts (60 Hz) or 380
volts (50 Hz) three phase.
THOMSON
AND HOWE ENERGY SYSTEMS INC.
8107 HIGHWAY 95A
KIMBERLEY, BRITISH COLUMBIA, CANADA
V1A 3L6
PH.: (250)
427-4326
FAX: (250) 427-3577
INDEX
·
INTRODUCTION AND ESSENTIAL READING....
................................…....3
·
THEORY OF OPERATION..... ..........................................................…….......6
·
DESCRIPTION AND SPECIFICATIONS... ......................................….........11
·
WIRING INSTRUCTIONS WITH EXAMPLES..
...............................………14
·
CASE HISTORY ........................................................................................…..15
·
COMMISSIONING INSTRUCTIONS ....................................................…...17
·
TROUBLESHOOTING INSTRUCTIONS........
....................................…......18
·
SPARE PARTS AND REPAIR SUPPLIES......................................................
22
·
WARRANTY AND DISCLAIMERS...............................................................
23
·
GLOSSARY OF TERMS.................................................................................
24
·
FACTORY OPTIONS. .........................................................................……...30
Dear Customer:
Congratulations on your purchase of a Thomson and Howe product.
You have bought the most advanced small hydro-electric governor system in
the world. We strongly recommend
that you read the rest of this manual at your earliest convenience in order to
make use of the governor’s advanced features and to maximize the usefulness of
your plant.
We wish you many years of reliable generation.
Do not hesitate to call or write us if you have questions or need advice.
Essential
note #1 - Main Loads
You must connect two equal sized loads to the outputs contained inside
the product “A2”. These loads
may only be simple resistance heating elements, and cannot have any control
devices (e.g. thermostats, switches) that may interrupt the connection.
These loads will be controlled internally by the governor.
They may be sized at up to a maximum of 6000 watts (@ 240 volts) each or
as large as required to match your maximum power generation,
whichever is smaller. These two
internally controlled loads are called the “main load” in this manual.
Essential
note #2 - For Plants of More Than 12 KW Output
If the amount of “main load” is not sufficient to absorb the maximum
output of the generator, then additional loads must be controlled externally by
the governor in order to prevent overspeeding.
These additional, external loads can be connected to relays that are
controlled from the governor by means of low voltage signal wires.
Any loads that are required to prevent overspeeding must always be
available in order to guarantee sufficient system load.
If it is necessary to waste the energy from certain of these loads in
order to assure sufficient loading for the generator, then these loads are known
as “waste loads”.
Essential
note #3 - Connecting Additional Externally Controlled Loads
a)
The externally controlled load to each step control output (the green
terminals on
the side) should not exceed about 1/2 of the “main load” (see note
#1). For
instance, if two 3 KW loads are directly connected to the governor, then
each step should not control more than 3 KW.
b)
When connecting waste load relays to the governor, start at control
output #8, working down towards
lower numbered outputs, connecting as much waste load
as necessary to prevent overspeeding.
Overspeeding will be prevented when the
total guaranteed external load plus the two main governor loads exceed
the maximum
output of the generator.
c)
For three phase systems, try to balance the controlled loads between the
three phases.
To balance loads usually requires a minimum of four relays.
d)
If the half-step output is used, only a solid state relay should be
connected to this
particular control output. Read
the manual carefully if this output is to be used.
95% of installations do not require this output to be
used.
e)
Useful user loads that the user wishes to have managed by the governor
should be
connected to step outputs #1 and up, with the highest priority
load connected to step output
#1, and working down
in priority as higher numbered step outputs
are used.
Essential
note #4 - Initial Computer Module Switch Positions
The internal module has four switches.
For most installations, turn #1 and #4 switches on, leave #3 switch off.
Essential
note #5 - Switch 2 Detail
If externally controlled loads are not used, or if they only control
loads that waste excess generation, then you may leave #2 switch off.
However, if you have even one useful load connected to a externally
controlled relay, then turn switch #2 on to inform the computer that external
loads should be turned on whenever possible.
Essential
not #6 - Main Load Vulnerability
The loads connected directly to the governor must be of high quality and
immune to shorting out. If these
loads burn or short out, then the “triac” solid state power devices may be
damaged and require awkward repair.
Essential
note #7 - Is the Governor Working?
Leaving aside any other considerations or complications, note that if
the frequency meter is indicating a steady 60 Hz (optionally 50 Hz), then the
governor is doing its prime function of governing the system frequency
correctly.
Essential
note # 8 - Reading the Load Meter
The load meter will read the amount of power delivered to the “main
loads” only, not the externally controlled loads. The power is read as a percentage of the maximum rating of
the main loads. For instance, if
two 3 KW loads are connected, and the meter reads 10% then the power going to
the two main loads is (3KW + 3KW) x 10% = 0.6 KW = 600 watts. Electricians - please note that reading the voltage output to
these two loads in order to calculate power output will provide erroneous
results. Use the load meter
provided.
Essential
note #9 - Why are the Red and Yellow Lights Dark?
Each red or yellow light will only light up if the governor has turned
that particular step output on, and if a complete control circuit exists from
that output to a externally controlled relay.
If for some reason, the control circuit is broken, this fact is
immediately obvious because the light will go dark unexpectedly.
If you wish the lights to indicate even if they are not controlling
relays, then you may install wire jumpers between the terminal pairs of unused
outputs.
Essential
note #10 - Main Load Sequence
The main load connected to terminals #3 and #4 will be turned on fully
by the computer first. The voltage
supplied to this load will increase from zero to maximum as the load meter
increases from 0 to 50%. From 50%
to 100% indication on the load meter, the first load will be held at maximum and
the second load connected to #5 and #6 will vary from zero to maximum voltage.
Essential
note #11 - The Green Light is Dark
The green light is a memory device.
Its function is to tell you that an abnormal operating condition has
occurred since the governor was last energized. It does not otherwise affect the operation of the governor.
It can be reset by the optional push-button, or by shutting the plant
down momentarily.
Essential
note #12 - The Percent Load Never Reads Very High and the Steps Refuse to Stay
on.
Do not blame the governor. The
governor cannot create power, it only manages the power available from the
generator. If insufficient power is
available, then the governor will automatically reduce the number of loads on to
try to maintain correct operating speed and frequency.
If the power is much less than expected, the first thing to check is the
penstock pressure.
Essential
note #13 - Additional load management
You might be interested in the product “C” if your site has any of
the characteristics listed below. The
product “C” will work on the same system as a product “A”, and control
eight additional loads without any control interconnections to the product
“A”.
a)
Loads to be managed that are remote from the intended site of the
governor.
b)
You require more than eight levels of load management.
c)
The loads are spread over a large area, such as a community
d)
You plan to operate the system from more than one source of power.
THEORY
OF OPERATION
GOVERNING
DEFINITION:
The definition of governing with mechanical equipment is the control of
speed. Since the speed of an A.C.
generator is synchronized exactly to the frequency of the power, governing of an
A.C. power system is synonymous with control of frequency.
A
COMMON EXAMPLE OF A GOVERNOR: Governing of power systems
is done by maintaining a precise balance between the power being generated and
the power being consumed at every moment in time.
One analogy for this process is that of a driver of a car on a highway.
He must constantly monitor the speed of the car and adjust the throttle
of the car to maintain constant speed. A
cruise control will do this function of speed control automatically for the man
and hence is a type of governor. Note
the following:
i.
The speed of the car is monitored by the governor (the person or the
cruise control).
ii.
Without adjustment, the speed of the car will increase if the demand for
power decreases (i.e. tail wind,
downhill slope).
iii.
Without adjustment, the speed of the car will decrease if the demand for
power
increases (i.e. head
wind, uphill slope).
iv.
The output from the engine will be adjusted by the governor to compensate
for changes in load when a change of speed is detected.
TRADITIONAL
HYDROPLANT GOVERNING The task of a traditional
mechanical water governor is conceptually identical to the above analogy, but it
is expressed a little differently:
i.
The frequency of the generator is monitored by the governor.
ii.
Without adjustment, the frequency of the generator will increase if the
demand for
power decreases.
iii. Without adjustment,
the frequency of the generator will decrease if the demand for power increases.
iv.
The output from the turbine will be adjusted by the governor to
compensate for changes in load when a change of frequency is detected.
A
MODERN ALTERNATIVE
An increasingly popular method is avoiding all mechanical equipment
required for controlling water. These
governors perform the basic governing function by automatically maintaining the
demand for power from a generator in balance with the amount of power can
supply.
The balance is maintained by control over lower priority loads that may
be adjusted to compensate for changes in turbine output or for any user switched
loads that are turned on or off elsewhere on the system.
ADVANTAGES
OF LOAD CONTROL GOVERNING The generator always
generates the maximum power possible. The
generation not immediately required is used up in secondary loads that are
controlled by electronic equipment. If
these secondary loads can be used for useful purposes, the overall system
efficiency can be extremely high, whether used with run-of-the-stream or water
storage capable sites. Other
advantages are as follows:
i.
Since the control is by electronic means, the response of the governor to
changes
in frequency can be faster and more accurate than mechanical means of
governing.
ii. Governing by
control of water is complicated by the effects of water hammer.
Water hammer results from having to accelerate and decelerate the moving
water in the power plant and penstock in order to vary the flow through the
turbine. These effects can be
severe if the water flow is changed too quickly.
Water hammer induced pressure fluctuations create governing difficulties
if not corrected for. Water hammer
problems are reduced in large hydro-power plants by keeping the length of the
pipelines as short as possible, by reducing the speed of operation of the
governor, (possible only if the loads change slowly enough), or by installing surge towers to absorb the impact of flow
changes. If the governing is done
by load control no quick changes are necessary.
iii.
No moving parts. Mechanical
governing requires relatively fast and accurate
mechanical movement. These
devices necessary to control water add to the
turbine expense.
iv.
The generally least expensive types of turbines do not have any simple
way to control water. Industrial pumps, for example, can be applied as low cost
turbines by operating
them backwards, but of course, do not have any inherent method for controlling water but must use
load control.
v.
Little or no custom engineering is required, because the governing action
is not affected by site dependent
characteristics such as length and size of the penstock.
T.H.E.S.
GOVERNOR FUNCTIONS
The Thomson and Howe Load Control Governors are designed to perform three
jobs in a hydro-electric installation: First
of all these governing systems will govern by load control very accurately.
But a governor system installation will also provide two more functions:
It will look around for additional loads to turn on in order to maximize
the usefulness of the plant -- this is known as load management; and also
it will prevent overloading of an hydro-electric plant by shedding loads at peak
demand periods or during low water -- this is know as peak demand control.
FREQUENCY
MONITORING
T.H.E.S. Load Control Governors monitor only the frequency of the power
system which is exactly the same at any point on the system.
Frequency is also proportional to the rotational speed of
your alternator. The Load
Control Governor will hence monitor and control the speed of your A.C. generator
from anywhere on the power system.
INSTALLATIONS
WITH A LARGE LOAD/GENERATION RATIO Peak demand control becomes most important on
systems that only have a small generator connected, since the loads are very
likely to exceed the output of the generator.
In extreme cases, only loads that must stay on no matter what (e.g.
inside lights) would be connected directly to the generator.
All other loads would be connected to relays so that they will be turned
off if the power is needed elsewhere.
INSTALLATIONS
WITH A SMALL LOAD/GENERATION RATIO In a
system that has a relatively oversized generator, the loads originally connected
are not so likely to exceed the output of the generator. Hence peak demand control is less important.
All user loads may be connected directly to the generator without fear of
overloading. The user may, however,
have a motivation to improve the economics of running the plant by finding
additional low priority loads to use up the excess generation.
This will require load management.
A
NUMERICAL EXAMPLE OF POWER DIVERSION A generator is producing
60 KW, delivering this power to 35.4 KW loads that the user has switched on at
this particular time. The governor
has main loads totaling 12 KW connected, and each of eight load management
relays has a load of 6 KW connected. Without
a Load Control Governor or controlled relays, the generator would run away into
overspeed because of the 24.6 KW excess power being generated;
However, the Load Control Governor will respond quickly and first of all
add on the 12 KW main governor load. There
still remains a surplus of 12.6 KW, so the Governor will quickly turn the three
relays on, creating an automatically controlled load of 12 + 3 x 6 = 30 KW plus
the user controlled load of 35.4 KW. The
5.4 KW excess load will be adjusted for by backing off the main load from 12 KW
back to 6.6 KW, exactly balancing generation and load.
60 KW generation =
35.4 KW (demand)
6.6 KW (main Governor load)
18.0 KW (three relay loads at 6 KW each)
SMALL
SYSTEM EXAMPLE
A 5 KW generator is running, supplying a single household.
The user has connected the loads as follows:
DEMAND- lights, convenience outlets (maximum load 5 KW, minimum load 0
KW)
MAIN CONTROLLER-two 2.5 KW hot water elements (large tank) switches to two 2.5 KW baseboard
heaters when the thermostat is hot. NO
thermostat on baseboards. If the
house gets too hot, install a switch to switch power
in the summer to the outside.
RELAY
#1 -
clothes dryer (small, no more than 2 KW)
RELAY #2 -
clothes washer (1.0 KW)
RELAY #3 -
kitchen fridge, deepfreeze (1.0 KW maximum)
RELAY #4 -
second hot water element (2 KW) insures hot water has this
level of priority. Thermostat
controlled.
RELAY #5 -
kitchen / bathroom baseboards on thermostats (maximum 2
KW)
RELAY #6 -
living room baseboards on thermostats (maximum 2 KW)
RELAY #7 -
bedroom baseboard heaters on thermostats (usually turned
off during the day, maximum 2 KW)
RELAY #8
spare
Note the following with regards to this example installation:
1.
Things that a person expects to have available on demand, lights, radio,
T.V., toaster, are directly
connected to the generator, but that these loads never exceed a
total of 5 KW at any one time, Providing peak demand control by
avoiding
overloads.
2.
The governor main loads are never turned off.
These loads ensure that the
generator will never overspeed due to too many loads being turned off.
3.
Note that the loads connected to the relays in this example never exceed
3 KW per step
(less than two/thirds of the 5 KW main governor loads).
4.
Note that the loads connected to the relays are in order of priority, and
that any of
these loads may be turned off if there is insufficient power.
OPERATING
RANGE
A load Control Governor can be used on any size generating system.
However, it can only maintain frequency control if the power system
always has a small surplus to sink into the Load Control Governor, otherwise,
the Load Control Governor would no longer have any load to maintain control
with. The system frequency could
drop because of an overload condition. Conversely,
the generator should not have a power surplus larger than the maximum that the
Load Control Governor system can sink, otherwise the frequency could rise
because of an underload condition.
CONSTANT
LOADS
A T.H.E.S. Load Control Governor system may, however, be used on a
generator of capacity larger than
the Load Control Governor load. In
this case, however, constant base loads must be connected continually to the
generator in order to reduce the maximum surplus power that could possibly
become available.
MAIN
UNIT OUTPUTS
The main unit has two direct high-power (SCR) outputs that finely control
the frequency by continually adjusting the output voltage throughout the range
from 0 to 230 volts as required. The
loads connected to these output(s) must be simple heating elements because of
the fluctuations (i.e. no motor-driven equipment).
The load connected to terminals #3 and #4 is of higher priority and will
come on first before the load connected to terminals #5 and #6.
MAIN
UNIT LOADS
Since the loads connected directly to the governor are subject to voltage
variations, and hence are limited to simple resistance elements, the Load
Control Governor system has the ability to prefer to turn on relay loads
whenever possible. The relay loads,
as they are turned on, reduce the power diverted to the main governor loads.
This preference is obtained by turning #2 module switch up.
SUGGESTIONS
FOR LOADS
The Load Control Governor needs guaranteed loads that are capable of
absorbing the output of the generator for long periods of time without problems.
A partial list of loads that can be considered follows, however, most
often guaranteed loads are simply waste loads, since this is simpler.
1.
Swimming pool heaters
2.
Concrete imbedded heating cables
3.
Hot water heating (with high temperature relief valve or pump).
4.
Soil heating cables or greenhouse heating
5.
Snow melting cables in driveways
6.
Furnace heating elements (with a backup heat source)
HALF
STEP RELAY
The Load Control Governor has a special output to control a relay
separate from the eight load management relays for some installations.
This relay may be sized up to two thirds of the total main load
connected. Since this relay is
switched quite frequently, it should be a solid - state relay and the load
should be considered as a lowest priority load, the same as the main loads.
This half - step load must also be always available for turning on.
REASONS
FOR USING THE HALF-STEP There are two reasons for
using this half step relay: First, on large systems, the maximum load that may
be connected to any (or all) of the eight load management relays is increased to
double the load connected to the half step load. This allows much higher power capability at little extra
cost; Second, on small systems, larger appliances may be controlled by relays
since the half step load turns off the instant that each of the eight relay
steps is turned on, reducing the impact of each relay load.
RELAY
PRIORITY
The Load Management Loads are switched remotely from the main unit by
means of 10 milli-amp current loops to controlled power relays.
One to eight relays may be turned on or off as available surplus power
permits, but lower numbered relays are turned on, and also the higher numbered
relays, if turned on, will be turned off first.
This priority step design can provide the user with the following
benefits:
1.
Since these eight steps are switched in strict order of priority, the
user can connect
more important loads to
the lower numbered steps, and less important loads to
the higher numbered steps. This
will ensure that the power that is available will
always go where it is most needed.
2.
On a three phase system, the user need only arrange relay controlled
single phase
loads on each of the phases to balance phase currents to an acceptable
amount. No expensive three phase Governor is
required.
3.
The use of relatively inexpensive relays to switch the majority of the
loads reduces
the overall cost, especially for larger plants.
4. The use of phase
switched devices such as triacs or SCRs crates large transient disturbances in
the power waveform. The use of
relays for the majority of the load reduces this effect to a low level.
TESTING
OF RELAY LOADS
If the “optimizer” is turned on (switch #2 in the up position), then
every minute or two the Governor will attempt to turn on the next lower priority
step not already turned on, using power available from the main load.
If enough power is available, the step will stay on,
If not, then the step will turn off and the Governor will wait until more
power is available before trying again. With
sufficient power, the process will end when all steps are on.
The low priority main load will hence be reduced as low as possible.
DESCRIPTION
AND SPECIFICATIONS
ENCLOSURE
The T.H.E.S. Load Control Governor is housed in a non-ventilated, gray
enamel painted steel enclosure. The
enclosure is 12 inches by 14 inches high by 6 inches deep.
The gaskets are foam rubber. The
door has a piano hinge on one side and two steel clamps on the other side.
FREQUENCY
METER
The front panel has a frequency meter which reads from 0 to 100 hertz
with 2% F.S. accuracy. The user should note that when the controller is functioning
normally, the controller is more accurate than the meter, however, the meter is
useful for monitoring fluctuations or abnormal situations.
LOAD
METER
The load meter on the right indicates the percentage of the main load
maximum power capability that is currently being used.
For instance: if 2 KW is being dumped into two 3 KW loads (totaling 6 KW)
connected to the main governor outputs, then this meter will read 33%.
If this dump power increases to 4 KW, then the meter will read 67 %.
LIGHTS
The
eight red lights indicate the status of the Load Management steps.
These lights will only indicate when the load management step turns on
and a relay is connected to that step’s terminals.
The lower left yellow light indicates the status of the half step.
This light otherwise behaves the same as the eight load management
lights. The lower right green light
is normally lit when the controller is functioning normally, it will go out if
the Load Controller is not supplied with power, or if the controller has
detected under 55 Hz or over 65 Hz for more than a few seconds, or if the time
error counter has overflowed. This
light will also flash if the computer discovers an internal failure.
SIDE
OF PANEL
The side of the panel has one terminal pair near the top.
This is the half step control output.
The eight lower terminal pairs are below the aluminum heat-sink, they are
arranged as follows:
1. 2.
3. 4.
5. 6.
7. 8.
The positive (source) terminal is always on the right and painted red.
The negative (drain) terminal is always on the left and silver in colour.
CONTROLS
Inside
the enclosure is a small control box with four switches.
The left-hand switch (#1) is the step speed adjustment, and selects
either normal (on) or slow (off) step switching speed.
If switch #2 is on, the computer will operate with a preference to turn
on relays in order to reduce the main unit loads (see “relay testing”).
The two right-hand switches set the frequency accuracy of the Controller.
Note that time-keeping and steady-state frequency accuracy is maintained
in any position.
SUPPLY
VOLTAGE
To terminals #1 and #2 inside governor.
This supply is used both for the governor electronics, and to power the
two main unit loads connected to terminals #3 through #6.
200 volts to 240 volts is acceptable for standard governors.
120 volts is the optional voltage.
GOVERNOR
INTERNAL POWER CONTROL CAPABILITY 3000
watts per output at 120 volts, 6000 watts per output at 240 volts, 6000 watts
per output at 208 volts.
ACCURACY
OF FREQUENCY CONTROL DURING LOAD CHANGES Full
governing action can be set for the following sudden frequency deviations:
plus or minus 4 hertz, 2 hertz, 1 hertz, or 0.5 hertz.
This is equivalent to setting the proportional gain in a typical process
controller. Due to the inclusion of
the equivalent of an integral term, these settings affect the immediate response
only, within a few seconds, the governor will return the frequency to 60 hertz
(optionally 50 Hz) no matter what the setting.
Large, sudden load changes requiring several relay step changes may cause
the frequency deviation to exceed these settings momentarily.
ACCURACY
OF STEADY STATE FREQUENCY CONTROL Standard
controllers are not tested for frequency accuracy since the quartz crystals have
inherently high accuracy. Sample
testing of unadjusted units indicate a typical accuracy of 0.005 Hz.
Optional calibrated units are supplied with an internal frequency
adjustment. Factory calibration is
usually accurate to 0.0003 Hz, or about 15 seconds per month with normal ambient
temperature changes. Temperature
changes will affect frequency slightly, so governors installed in unheated
powerhouses will not have as high a frequency accuracy as governors installed in
constant ambient temperatures.
INTEGRAL
TERM RESET SPEED
If a load change results in a new frequency due to the action of the
proportional term, the integral term will reduce the frequency error by half
every 1.5 seconds.
CLOCKS
WILL RETURN TO CORRECT TIME AFTER LOSS OF GOVERNING The timekeeper (which is not the integral term mentioned
above) is allowed a maximum 0.1 Hz deviation to correct clock times following a
loss of governor control due to overspeeding or overloading.
0.1 Hz translates to 6 seconds of correction every hour, 17 minutes every
week.
POWER
CONSUMPTION
10 watts (1 watt for newer CMOS modules), plus approximately 0.5% of the
power delivered to the load at 240 volts.
SLEW
RATE
Triac loads can typically change from zero load to full load (or
vice-versa) in 3 cycles (50 milli-seconds) for normal frequency changes.
With switch #1 in the fast (up) position, step loads will step in at 1/4
second intervals for small errors in frequency (2 seconds for all eight). Large errors in frequency trigger a double speed step change
rate of 125 milli-seconds per step, higher errors trigger a triple speed
stepping rate of 83 milli-seconds per step (2/3 of a second for all eight
steps). With switch #1 in the slow
(down) position, all step switching times are four times slower.
RELAY
TESTING
The Controller will normally try to turn main steps on at the rate of one
per minute if power is being delivered to the main unit loads.
If a step turns off after being turned on due to insufficient power, then
approximately 10 to 25% more power as a percentage of the main load connected
must become available before it tries again.
In any case a try is made every half hour to avoid “locking-up”.
This testing action will only occur if switch #2 is in the up position.
If the user does not care how many relays are turned on (e.g. all relay
power is wasted anyway), then he would leave switch #2 off.
RELAY
OUTPUTS ELECTRICAL SPECIFICATIONS Each positive output is
sourced from a switched 20 volt D.C. unregulated source through a 470 ohm
resistor and a light emitting diode. The
D.C. supply to all outputs will be energized only when the computer is reset and
activated in order to avoid spurious operations.
Each negative output is drained back through a 1000 ohm resistor and a
transistor switch to ground (chassis) potential.
Clamp diodes are used on the negative lines to ground to clamp transient
voltages. Common output control
lines are not permitted. Each output must be a separate twisted pair.
Shielded cables are recommended if the routing of the wires is held
within one inch of power conductors for more than 2 feet, or if the cable route
is more than 100 feet from one building to another.
Connect the cable shield to the chassis of the governor and also to the
chassis of external relays.
WIRING
INSTRUCTIONS
CONNECTIONS
The controller usually needs no connections other than the high-voltage
power supply and load connections, plus the low-voltage relay control wiring if
used. The controller can be
situated anywhere on the system; It
does not have to be installed in the powerhouse.
We actually prefer that the Controller be installed close to the loads to
allow more convenient load control.
POWER
SUPPLY
The load controller main unit requires a single phase power supply rated
to carry the current rating of the loads connected.
The following pages provide the internal wiring of the product “A2”
panel as well as many suggested wiring diagrams.
RELAY
WIRING
Note that the relay control wiring is at low voltage and may be wired
with telephone or ‘bell’ wire. Polarity
is important, red to red, silver to silver.
Shielded wire may be necessary for long runs between buildings, or if
signal wires share conduit with power conductors.
A
CASE HISTORY
The following case history is a combination of many different
installations. None of the names
are real, but the basic outline has occurred many times.
John Smith owned a remote hunting and fishing cabin that he wanted to
turn into an all-season resort. The
key to this ambition was to find an alternative to the noisy, expensive, and old
diesel power plant. John hired ABC
Hydro-electric Consultants to provide a proposal on a nearby waterfall.
ABC calculated that a plant could be built on the waterfall that would
provide almost for all year a 24 KW power output. John decided to proceed and ABC then issued the
specifications to equipment suppliers for quotes.
They specified a mechanical type governor for frequency control.
ABC had several phone calls from some of the suppliers that had received
the request for tenders. These
suppliers preferred to quote using a Thomson and Howe Load Control Governor.
ABC subsequently modified the specifications to include this approach.
The lowest bids received used the Load Controller and one of theses
suppliers was selected.
This installation is sometimes typical in that the Load Control Governor
was quoted as a direct replacement for a mechanical governor.
Hence simplicity and low first cost of installation was most important in
the quote. In addition, no
discussions were held with the owner to optimize the system by discovering what
uses he had planned for the power.
The Load Control Governor was installed with a main unit load of two 6
KW heating elements that wasted energy into the turbine water, and one dual
relay unit. Each of these two
relays controlled another 6 KW waste element.
These relays were connected to steps #7 and #8, as is correct for waste
loads. These loads totaled 24 KW,
enough load to ensure that the plant would not be under-loaded.
John already had electric lights, convenience outlets, toaster, washer
and dryer connected (peak demand 8 KW). He
then also connected an electric stove (peak 10 KW) and 6 KW of thermostatic
baseboard heating. His peak
non-governor load was hence kept below 24 KW to avoid overloading the plant.
However, most of the time, he did not use the power for useful purposes.
INITIAL
CONFIGURATION
GENERATOR
ALLOWABLE
WASTE LOAD AVERAGE
USEFUL
OUTPUT
USER’S
LOADS
CONNECTED
GENERATION
24
24
24
5 KW estimated
Then winter came. John
found that he was burning wood because 6 KW of baseboard heating was not enough,
yet, if he increased the number of baseboard units, he would run the danger of
overloading his plant.
John then re-read this manual and realized that most of his loads could
be interrupted by load management relays, allowing far more loads to be
connected. He ordered four relays
and connected the 6 KW of baseboards he had and 10 KW of additional baseboards
as follows:
Step
#1 ---- 4 Kw of baseboard heating
Step
#2 ---- 4 Kw of baseboard heating
Step
#3 ---- 4 Kw of baseboard heating
Step
#4 ---- 4 Kw of baseboard heating
Because he had now installed relays on his original 6KW set of
baseboards, he was free to add another 6 KW of uncontrolled loads elsewhere on
the system, without fear of overloading the generator.
WINTER
CONFIGURATION
GENERATOR
USER’S
LOADS WASTE LOADS
AVERAGE USEFUL
OUTPUT
ALLOWABLE
CONNECTED GENERATION
24
40
24
12 KW (much better)
Then summer came. John
found that he was not using the energy because it was warm, hence his return on
investment was low. Also, his
guests were using more and more load on demand (e.g. hair dryers at 8:00 A.M.),
so he had to move more loads onto relays. John
decided to buy enough relays to add the following loads to attract more business
while at the same time, avoiding overload problems:
Step #1 ---- Stove (10 KW peak, almost always lower)
Step #2 ---- Washer / dryer (peak 5 KW)
Step #3 ---- Hot water heaters (peak 8 KW)
Step #4 ---- Baseboard heaters (peak 8 KW)
Step #5 ---- Baseboard heaters (peak 8 KW)
Step #6 ---- Hot-tub (peak 8 KW)
Step #7 ---- Swimming pool (peak 8 KW)
Step #8 ---- Waste heat elements (9 KW)
Halfstep --- Waste heat elements (3 KW)
Governor main loads ---- Waste heat elements (12 KW)
In addition to the loads listed above, he was also to connect 24 KW of
demand load elsewhere, so that the total useful load connected became 24 + 10 +
5 + 8 + 8 + 8 + 8 + 8 = 79 KW
GOVERNOR
ALLOWABLE WASTE LOADS
AVERAGE USEFUL
OUTPUT
USER’S LOADS
CONNECTED
GENERATION
24
79
24
21 KW (close to maximum)
COMMISSIONING
INSTRUCTIONS
PRE START-UP CHECKLIST
1.
Is the wiring correct to the governor panel?
2.
Is the governor panel the correct frequency (50 or 60 hertz)?
3.
Is the governor panel the correct voltage for the power being supplied to
it?
4.
Are there two loads of the correct voltage connected to the outputs of
the governor, nor more
than 4000 watts each @ 120 volts; 7500 watts each @ 208
volts, or 8000 watts each @ 240 volts?
5.
Are the following computer module switches set as follows?
Sw #1 - off, Sw #3 - off, Sw #4 - on
6.
Is water covering the immersion heaters, if used?
7.
Have all loads been electrically checked with an ohmmeter to ensure no
leakage to ground
and the correct element resistance?
8.
Has all electrical equipment been properly grounded to the mechanical
equipment
(including the immersion heater tank if used)?
After all wiring has been completed, ensure that the generator runs and
generates normally with no power supplied to the Load Control Governor.
This test will ensure that the generator works and that the basic wiring
was done correctly. When performing this test, be sure that the generator does
not overspeed by controlling water flow. Check
the generator voltage and ensure that it is reasonable close to what is
expected. Only after the power
system is given a clean bill of health should the owner perform the following
sequence:
1.
Shut down the generator.
2.
Close the breaker to the Load Control Governor.
3.
Gradually open the water valve and start the generator, let the generator
speed up
until the Load Control Governor starts pulling load.
4.
The frequency should then be very close to 60 Hz (optionally 50 Hz) and
the Load Control
Governor load meter should be indicating delivery of some surplus power
to the main loads.
5.
Gradually increase the output from the generator, watching that the steps
do come
in and that they draw away the excess power.
The frequency should not have to
go above 62 hertz while this is being done.
6.
Once the generator is at full output, try to increase the performance of
the Governor beyond the
minimum now set. Do this by
following the lettered instructions
below. As soon as the governor
seems to become unstable (lights
flicker, frequency fluctuates, or it emits a ragged noise instead of a
steady buzz),
then go back to the previous step to obtain smooth performance.
a)
Put switch #4 to the off position and put switch #3 switch up.
This sets a 1 hertz
frequency control.