Functionality Note

The Soft Load Automatic Transfer Switch will parallel one emergency generator to the utility. It cannot be used for controlling multiple generators or having multiple soft load systems control a single generator. This usually necessitates obtaining approval from the local distribution utility company and meeting the IEEE 1547 Standard for utility interconnection requirements. The generator set must be equipped with an automatic isochronous governor and solid state voltage regulator controls, each suitable for parallel with utility operation

PART 1 GENERAL

1.1Scope

Furnish and install a soft load transfer switch (ZTSSL) with number of poles, amperage (4000 amps maximum), voltage and withstand/close-on ratings as shown on the plans. All components, testing, and services specified or required for a complete operable system shall be included and shall be the product of the same manufacturer.

1.2 General Design Requirements:

  1. The ZTSSL shall consist of a power transfer switch, genset controller (GCP), and one utility/generator power management and protection (G30), The ZTSSL shall provide load transfer between the utility and generator source with the following selectable operating modes:

Transition Modes:

  1. Closed (<100mS)
  2. Soft (1 second to 16 minutes)
  3. Open

Transfer Modes:

  1. Automatic (Emergency Standby)
  2. Islanded
  3. Peak Shave (Continuous Parallel with Utility)
  4. Base-load
  5. Import / Export

KW Demand Mode: ON/ENABLE – OFF/DISABLE

  1. The GCP shall retain master control of the Power Transfer Switch for all transfer functions, including conventional open transition; closed transition and soft load transfer operations. Upon loss of a power source, the GCP controller shall transfer the load to the generator via open transition (no overlap during load transfer).

C. The GCP shall handle the user interface for all control.All protective function settings shall be provided by a separate utility grade multi-function G30 relay. The GCP shall also handle the following functions:

1) Transmission of all generator alarm conditions, synchronization of power sources, voltage matching, VAR/power factor control, and generator loading/unloading control algorithms.

2)Generation of analog voltage signals and/or a pulse width modulated signal to drive external speed control, and voltage regulator.

3)All GCP screen displays, operating labels, and operator’s manuals shall be available in English and Spanish at a minimum.

D.Utility and Generator Power Protection and Management (G30)

The G30 shall monitor the utility power parameters and provide protective relaying functions, including relay outputs for external circuit breaker tripping control. The protective relaying shall meet the requirements of IEEE 1547 Standard for utility interconnections. The utility power parameters and alarming information shall be serially communicated to the optional EnerVistaTM ViewPoint Monitoring software for control and display.

E.Soft Load System Block Diagram

The ZTSSL Softload Transfer switch shall be designed to control a single generator in parallel with a single utility supply. The GCP provides the softload control, while the Multilin G30 provides Utility-grade protection for both the Generator and Utility Supply. The Softload Transfer Switch shall send speed increase/decrease and voltage increase/decrease signals to the Genset-mounted control panel for synchronizing and load control functions

1.3 Related Sections

A. Section 16XXX: Generators

B. Section 16XXX:

1.4Application Codes and Standards

  1. IEC 60947-6-1 Low-voltage Switchgear and Control gear; Multifunction equipment; Automatic Transfer Switching Equipment.
  2. IEEE Standard 446 – IEEE Recommended Practice for Emergency and Standby Power Systems for Commercial and Industrial Applications.
  1. IEEE Standard 1547 – Standard for Interconnecting Distributed Resources with Electric Power Systems.
  2. IEEE Standard 1547.1 – Standard Conformance Test Procedures for Equipment Interconnecting Distributed Resources with Electric Power Systems.
  3. National Fire Protection Association (NFPA). NFPA - 70 - National Electrical Code
  4. NFPA -110 - Emergency and Standby Power Systems
  5. NFPA - 99 - Essential Electrical Systems for Health Care Facilities.
  6. NEMA Standard ICS10-1993 (formerly ICS2-447) - AC Automatic Transfer Switches
  7. UL 1008 – Standard for Transfer Switch Equipment
  8. UL 508 Industrial Control Equipment
  9. UL 891 Dead Front Switchboards for circuit breaker versions

1.5Manufacturer’s Qualifications

The Soft Load Automatic Transfer Switch shall be GE Zenith Controls Model ZTSSL. Any alternate shall be submitted to the consulting engineer for approval at least 10 days prior to bid. Alternate bids must list any deviations from this specification.

PART 2 - PRODUCTS

2.1 Power Transfer Switch

  1. The power transfer switch shall be electrically operated and mechanically held. The electrical operator shall be a momentarily energized, solenoid mechanism. Main operators that include over-current disconnect devices; linear motors or gears shall not be acceptable.
  2. All transfer switch ratings shall use the same kind of main operator for ease of maintenance and commonality of parts.
  3. The switch shall be positively locked and unaffected by momentary outages, so that contact pressure is maintained at a constant value and contact temperature rise is minimized for maximum reliability and operating life.
  4. All main contacts shall be silver composition. Switches rated 600 amperes and above shall have segmented construction for high withstand and close-on capability and be protected by separate arcing contacts.
  5. Inspection of all contacts shall be possible from the front of the switch without disassembly of operating linkages and without disconnection of power conductors.
  1. Designs utilizing components of molded-case circuit breakers, contactors, or parts thereof, which are not intended for continuous duty, repetitive switching, transfer between two active power sources, or field maintenance is not acceptable.
  2. Where neutral conductors are to be solidly connected as shown on the plans, a neutral conductor plate with fully rated AL-CU pressure connectors shall be provided.

2.2 Transfer Switch and Soft Load Controller (GCP)

  1. The Transfer Switch Control and Load Control functions shall reside in one integrated control unit (GCP).
  2. The Transfer Switch and loading functions, sensing and logic shall be incorporated in a single microprocessor controller for maximum reliability, minimum maintenance.
  3. The voltage sensing shall be true RMS type and shall be accurate to 1% of nominal voltage. Frequency sensing shall be accurate to 1%. The controller shall be capable of operating over a temperature range of -20 to +70 degrees C and storage from -30 to +80 degrees C.
  4. The controller shall be connected to the transfer switch by an interconnecting wiring harness. The harness shall include a keyed disconnect plug to enable the controller to be disconnected from the transfer switch for routine maintenance. Sensing and control logic shall be provided on multi-layer printed circuit boards. Interfacing relays shall be industrial grade plug-in type with dust covers. The controller shall be enclosed with a protective cover and be mounted separately from the transfer switch unit for safety and ease of maintenance.
  5. All customer connections shall be wired to a terminal block to simplify field-wiring connections.
  6. The controller shall meet or exceed the requirements for Electromagnetic Compatibility (EMC) as follows:

1)IEEE472 (ANSI C37.90A) Ring Wave Test.

2)ENC55011 1991 Class A Conducted and Radiated Emission.

3)EN61000-4-2 Electrostatic Discharge Immunity, Direct Contact & Air Discharge.

4)EN61000-4-3 Radiated Electromagnetic Field Immunity.

5)EN61000-4-4 Electrical Fast Transient Immunity.

6)EN61000-4-5 Surge Immunity.

7)ENV50141 HF Conducted Disturbances Immunity.

2.3 Transfer Switch and Soft Load Controller (GCP) Display and Keypad

A two-line, 16 character LED display and keypad shall be an integral part of the controller for viewing all available data and setting desired open delayed transition and closed transition operational parameters. The following parameters shall only be adjustable via keypad on the controller. DIP-switch adjustment is not acceptable.

1)Nominal line voltage and frequency

2)Single or three phase CT sensing

3)Operating parameter protection

All instructions and controller settings shall be easily accessible, readable and accomplished.

2.4 Transfer Switch and Genset Controller (GCP) - Voltage, Frequency and Phase Rotation Sensing

A.Voltage and frequency on both the normal and emergency sources shall be continuously monitored, with pickup, dropout and trip setting capabilities.

B.Repetitive accuracy of all settings shall be within ± 0.5 % over an operating temperature range of -20 C to 70 C.

C.Voltage and frequency settings shall be field adjustable in 1% increments with the display and keypad.

D.Source differential sensing shall be provided for all operating modes where the utility and the generator are paralleled (load is simultaneously connected to both sources). The GCP shall enable paralleled transfer/re-transfer between live sources only when the two sources have a maximum voltage differential of 5 % frequency differential of 0.2 Hz with the sourcesbeing within 5 electrical degrees.

E.The GCP shall be capable of sensing the phase rotation of both the normal and emergency sources.

  1. Source status screens shall be provided on the LED display described below for both normal & emergency to provide digital readout of voltage per phase and frequency.
  2. The GCP shall include a synchronizing check function to ensure phase, voltage and frequency matching of both power sources. This function shall inhibit paralleling the sources until the voltage is within 5 %, the frequency to within 0.2 Hz and the phase angle difference reduces to 5 degrees and is approaching zero.

2.5 Transfer Switch and Soft Load Controller (GCP)- Time Delays

  1. An adjustable time delay of 0.5 to 99.9 seconds shall be provided to override momentary normal source outages and delay all transfer and engine starting signals.

B.A load ramping rate shall be adjustable from 0.1% to 100% per second during transfer of load either from generator to utility or from utility to generator.

C.An adjustable time delay of 0.5 to 99.9 seconds to override momentary emergency source outage to delay all retransfer signals during initial loading of engine generator set.

D.Time delay shall be provided on re-transfer to normal. The time delays shall be adjustable from 1 to 3600 seconds. Time delay shall be automatically bypassed if the emergency source fails and the normal source is acceptable.

E.A time delay shall be provided on shut down of engine generator for cool down, adjustable from 1 to 3600 seconds.

F.A time delay activated output signal shall also be provided to drive an external relay(s) for elevator pre-signal control. The controller shall have the ability to activate an adjustable 0 to 60 second time delay in either direction.

G.The controller shall also include a built-in 10 to 999 seconds time delay on failure to synchronize normal and emergency sources prior to soft load transfer.

H.All GCP time delays shall be adjustable in either 0.1 or 1-second increments by using the LED display and keypad located on the enclosure door. The time delay value displayed on the LED or remote device shall be the remaining time until the next event occurs.

2.6Transfer Switch and Genset Controller (GCP)– Additional Features

A.A SPST contact, rated 2 amps at 24VDC, shall be provided for a low-voltage engine start signal. The start signal shall prevent dry cranking of the engine by requiring the generator set to reach proper output, and run for the duration of the cool down setting, regardless of whether the normal source restores before the load is transferred.

B.System Status-The controller display shall include messaging showing current operational processes such as timers timing down, alarm conditions, etc.

C.Self-Diagnostics - The controller shall show diagnostic messages for the purpose of detecting system errors. Messaging shall provide information on the status-input signals to the controller, which may be preventing load transfer commands from being completed.

The following features shall be available as required by the user:

D. Calendar Clock with Two Programmable Channels, Provide:

D.1Engine Exerciser - A separate exerciser timer module shall be provided for engine exerciser. The engine exerciser shall allow the user to program up to 400 different exercise routines. For each routine, the user shall be able to:

1)Enable or disable the exercise routine.

2)Set the start time

-time of day

-day of week

-week of month (1st, 2nd, 3rd, 4th, alternate or every)

-set the duration of the run

At the end of the specified duration the switch shall transfer the load back to normal and run the generator for the specified cool down period. A 6-year life battery that supplies power to the real time clock in the event of a power loss will maintain all time and date information. Timer programs shall be stored in non-volatile memory.

3)All exerciser timer programs shall be stored without use of additional controller EEPROM memory.

4)Daylight Savings Time?

D.2 kW Demand programmable Period per the contract with local utility for KW Demand Operation.

2.7Transfer Switch and Genset Controller (GCP) - Soft Load Control:

  1. All soft load control functions shall be integral part of the GCP.
  2. The GCP shall included a 2 x 16 LED display with touch sensitive membrane keypad for viewing and setting all programmable parameters in the GCPGCP shall be capable of operating over a temperature of –-20 to +70 degrees centigrade.
  3. The GCP shall be capable of displaying the following:

1)A digital multicolor LED synchroscope shall be provided to display the relative phase relationship between the utility and generator sources.

2) A digital display, showing power in both kW of total load, shall be provided for utility and generator sources.

3)Real, and reactive power, power factor active energy (kWh), line-to-line and/or line-to-neutral voltage, phase current, maximum current, frequency shall be displayed for generator power source.

4)Voltage, current, real power, and power factor shall be displayed for utility power source.

5)Active displays shall indicate source acceptability, circuit breaker and transfer switch positions.

6)Battery Voltage

7)Operating Hours

8)Engine Start Counter

9)Screens shall contain three levels of security to protect against unauthorized viewing or tampering of sensitive data.

10)An event and setup log shall be provided which captures the following information:

-Transfer switch events

-Power source status

-Engine Start/Stop

-Modes of operation

-Alarms (protective relay status)

The log shall capable of storing up to 50 events with documentation of with time and date stamp.

11)GCP protective functions shall be viewable from front panel LCD display.

D.The GCP shall contain the following inputs and outputs:

1)Analog output for governor control: fully adjustable up to +/- 9.0 VDC; or 10.0 Vpk, 500 Hz pulse width modulated (PWM).
2)Analog output for voltage regulator control: adjustable from 0 VDC to +/- 9 VDC.
3)Three relay contact outputs, form A, rated 2 amps @ 24 VDC, 0.3 amp @ 110 VDC, 2 amp @ 120 VAC to provide the following control and indication:
  1. Control of alarm horn-Provision
  2. Ready for operation-Provision
  3. Engine Start Signal

4)Sixteen (16) configurable discrete alarm inputs.

5)Seven (7) configurable/programmable output relays.

6)Three (3) configurable 0/4-20mA analog measuring inputs.

7)Two (2) configurable Pt100 analog measuring inputs.

8)Two (2) configurable VDO analog measuring inputs.

E.GCP shall have provisions for future integrated communication to engine controllers including (via CAN bus) standard SAE J1939, Deutz EMR, Scania S6, MTU MDEC; (via RS232) CAT CCM interface.

2.8Utility and Generator Power Protection and Management (G30)

  1. The Utility and Generator Power Protection and Management (G30) shall be an integral device. The Utility and Generator Protection and Management device shall meet the following requirements:

1)Utility Grade rated device. Industrial grade devices are not acceptable.

2)Capable of secondary, hot swappable, redundant power supply. Non- hot swappable power supplies are not acceptable.

3)Consist of modular design to easily facilitate upgrading or repair by replacement of modules. Non-Modular devices not acceptable.

4)Three (3) communication ports that operate independently and simultaneously. They shall be arranged:

i)One (1) RS232 port shall be front accessible. Port shall support ModBus RTU at 19.2kbps protocol.

ii)One (1) RS485 port shall support ModBus RTU and DNP 3.0 protocols capable of baud rates up to 115kbps.

iii)One (1) 10 Mbps Ethernet port supporting Ethernet Global Data (EGD), IEC 61850, MMS/UCA2, ModBus/TCP, and DNP 3.0 or IEC 60870 protocols. The port shall be 10/100BaseT.

5)The faceplate shall include an alphanumeric vacuum florescent display.

6)Contain an embedded web server and is capable of transferring web pages to a web browser. Web server accessed via the integrated Ethernet port. Web pages are available showing DNP and IEC 60870-5-104 points list, ModBus registers, Event Recorders, and Fault reports.

7)RMS current, voltage, real power (watts), reactive power (VAR), and apparent power (VA) sensing shall be accurate to no more than +/-1% of nominal. Watt-Hours (positive and Negative), and VAR-Hours (positive and negative) sensing shall be accurate to no more than +/- 2% of reading. Frequency sensing shall be accurate to no more than +/-0.05Hz.

8)Shall be capable of operating over a temperature range of -40 to +60 degrees C and storage from -40 to +80 degrees C.

9)The controller shall meet or exceed the requirements for Electromagnetic Compatibility (EMC) as follows:

10) EN61000-4-2 Electrostatic Discharge Immunity, Direct Contact & Air Discharge.

11) EN61000-4-3 Radiated Electromagnetic Field Immunity.

12) EN61000-4-4 Electrical Fast Transient Immunity.

13) EN61000-4-5 Surge Immunity.

14) IEC 61000-4-6 Conducted RFI.

15) IEC 610004-8 Power Frequency Magnetic Field Immunity

16) IEC 610004-9 Pulse Magnetic Field Immunity

17) ENV50141 HF Conducted Disturbances Immunity.

18) IEC 61000-4-12 Oscillatory Transient.

The controller shall meet or exceed the following approvals:

1)UL listed for USA and Canada

2)CE listed per LVD 73/23/EEC

3)CE listed per EMC 81/336/EEC

4)CE listed per IEC 1010-1

5)CE listed per EN 50081-2

6)CE listed per EN 50082-2

  1. Have the capability of monitoring all the power parameters for both power sources. Parameters shall be able to be monitored remotely by optional EnerVistaTM ViewPoint Monitoring software screens.
  1. The following protective functions shall be provided for programming (in any combination) by the user:

C1.Utility protection and management: