Nuvation Energy NUVSSG-1250-100 User manual

Nuvation Energy High-Voltage BMS
Product Manual
Document ID: NE-PM-003 | Revision: 1.2, 2021-03-03
BMS Software Version: Curie Update 1
© 2021 Nuvation Energy

Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê2
1.1. About this Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê2
2. Battery Topology Terminology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê3
3. System Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê4
3.1. Stack Switchgear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê7
3.2. Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê8
3.2.1. Stack Controller and Power Interface. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê8
3.2.2. Current Measuring Shunt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê8
3.2.3. DC Contactors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê8
3.2.4. Pre-Charge Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê9
3.2.5. Fuses. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê9
3.2.6. Safety Relay (for E-Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê9
3.3. Cell Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê10
4. Installation Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê11
4.1. Stack Switchgear Mechanical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê11
4.1.1. Dimensions and Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê11
4.1.2. Installation Location and Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê12
4.1.3. Mounting Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê12
4.2. Stack Switchgear Electrical Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê15
4.2.1. Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê15
4.2.2. Ensure system is de-energized . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê16
4.2.3. Grounding the Stack Switchgear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê17
4.2.4. Connect Power In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê18
4.2.5. Connect Fan Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê19
4.2.6. Connect E-Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê20
4.2.7. Connect Ethernet. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê22
4.2.8. Connect Link Bus. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê23
4.2.9. Connect Battery Stack and DC Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê23
4.3. Cell Interface Mechanical Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê25
4.3.1. Dimensions and Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê25
4.3.2. Installation Location and Position . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê26
4.3.3. Mounting Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê27
4.4. Cell Interface Electrical Connections. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê28
4.4.1. Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê28
4.4.2. Connect Temperature Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê29
4.4.3. Connect Battery Cells Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê30
4.4.4. Connect the Link Bus Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê36
4.5. First Power-up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê37
4.5.1. Status LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê38
5. Setting up the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê40
5.1. Install the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê40
5.2. Connect to the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê41

6. Using the Operator Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê44
6.1. The Dashboard Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê44
6.1.1. Warnings and Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê44
6.1.2. Stack Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê45
6.1.3. Stack Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê45
6.1.4. State-of-Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê45
6.1.5. Depth-of-Discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê46
6.1.6. Cell Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê46
6.1.7. Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê47
6.1.8. Nuvation Energy BMS Status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê48
6.2. The Details Tab . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê51
6.2.1. Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê51
6.2.2. Battery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê51
6.2.3. Current Limiter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê52
6.2.4. Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê52
6.2.5. Cell Voltages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê53
6.2.6. Thermistor Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê54
6.2.7. Open Wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê55
6.3. The Menu Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê57
6.3.1. Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê57
6.3.2. Service. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê57
6.3.3. Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê58
6.3.4. Locking and Unlocking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê59
6.3.5. About. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê60
6.4. The Status Banner . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê62
6.4.1. Service Lockout Indication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê62
6.4.2. Communication Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê62
7. Communication Protocols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê63
7.1. Modbus Protocol Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê63
7.1.1. Modbus TCP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê63
7.1.2. Implemented MESA Models. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê63
7.1.3. MESA Model Structure and Nomenclature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê64
7.1.4. Operational Cases for MESA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê65
7.1.5. Accessing MESA Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê68
8. External Interfaces. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê71
8.1. Stack Switchgear. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê71
8.1.1. Battery Stack and DC Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê71
8.1.2. Ethernet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê71
8.1.3. Link Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê72
8.1.4. E-Stop . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê72
8.1.5. Fan Control. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê73
8.1.6. Power In. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê73
8.2. Cell Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê75
8.2.1. Battery Cells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê75

8.2.2. Temperature Sensors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê78
8.2.3. Link In . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê79
8.2.4. Link Out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê80
9. Servicing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê82
10. Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê83
10.1. Faults and Initialization Issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê83
10.1.1. Cell Voltage Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê83
10.1.2. Stack Voltage Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê84
10.1.3. Thermal Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê85
10.1.4. Stack Current Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê85
10.1.5. Pre-charge Faults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê86
10.1.6. Contactor Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê86
10.1.7. Diagnostics Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê87
10.1.8. Breaker Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê89
10.1.9. Watchdog Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê89
10.1.10. Miscellaneous Faults. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê91
10.2. Lost/Forgotten IP Address. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê91
10.2.1. Wireshark (Windows/Linux) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê92
10.2.2. Netdiscover (Linux only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê92
Appendix A: Operating Limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê93
Stack Switchgear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê93
External Specifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê93
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê93
Environmental Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê94
Standards and Certifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê94
Cell Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê95
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê95
Environmental Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê96
Standards and Certifications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê96
Maximum Stack Deployment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê96
Appendix B: Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê98
Stack Switchgear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê98
Cell Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê98
Appendix C: Best Practices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê100
Excess Cable Management. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê100
System Noise. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê100
DC Filtering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê101
Link Bus Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê102
Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ê105

The content in this document must be followed in order to ensure safe operation of Nuvation
Energy BMS.
Do NOT energize the system until all connections to the Stack Switchgear unit
and Cell Interface modules have been made.

The wiring of the battery cell voltage and temperature sensing should be
verified before connecting to the Cell Interface modules. The temperature
sensing must be isolated from the cell voltage sensing. Although the Cell
Interface includes protective circuitry to make it more resilient to brief wiring
errors, the same circuitry can result in the battery cells being slowly
discharged. Over time, these wiring errors can cause damage to the Cell
Interface and/or the cells.
Properly insulate or remove any unused wires. Unused wires can couple
excessive system noise into Nuvation Energy BMS which can disrupt
communication and lead to undesirable behaviors.
Insulated handling is required of any connector carrying potentials over 60 V
DC relative to chassis.
Please be aware of high voltages present in your system and follow all
necessary safety precautions.

Nuvation Energy BMS relies on your system charger to charge the battery
cells; do not leave your charger off while Nuvation Energy BMS is powered
from the stack for prolonged periods of time. Nuvation Energy BMS should be
shut down when the system is in storage to minimize the drain on the cells.
The provided module enclosures are not fire enclosures.
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1. Introduction
Thank you for choosing Nuvation Energy BMS.
Nuvation Energy’s Stack Switchgear provides an integrated battery stack management solution that
includes all the hardware and software required to integrate a battery stack into your energy storage
system. Each Stack Switchgear unit contains Nuvation Energy High-Voltage BMS modules and is
designed to be used with other products in the Nuvation Energy BMS family.
1.1. About this Manual
This Nuvation Energy High-Voltage BMS: Product Manual is a comprehensive manual, providing:
▪Details about all the features offered by your Nuvation Energy High-Voltage BMS
▪Mounting and wiring instructions to install this product safely
▪Guidance on integrating the device into your energy storage system
▪Guidance on operating the Nuvation Energy BMS Operator Interface
This document applies to Nuvation Energy BMS Curie Update 1 software release
(Firmware version 4.106.1, Operator Interface version 0.56.1). Content may be
inaccurate or incomplete for other versions.
We thrive on your feedback and what we build is driven by your input.
Please submit support tickets to [email protected].
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2. Battery Topology Terminology
Energy storage systems are hierarchical in nature. Nuvation Energy has adopted the following
definitions for battery pack topology:
Cell
A Cell is the smallest unit of energy storage distinguishable by the battery management system.
One Cell, as defined from the perspective of the BMS, may actually consist of one or more
electrochemical cells connected in parallel. This subtlety is reflected in the nomenclature for
completeness. For example, a "1p" Cell refers to a single electrochemical cell, while a "2p" Cell
refers to two electrochemical cells connected together in parallel. From the perspective of the BMS,
these topologies appear identical except for the capacity of the Cells.
Group
A Group is a set of Cells connected in series and managed together. For example, 12 "1p" Cells in
series are referred to as a "12s1p" Group, while 16 "2p" Cells in series are referred to as a "16s2p"
Group. Grouping of Cells is highly application-specific and is defined in how BMS hardware
interfaces are physically wired up to Cells.
Stack
A Stack is one or more Groups connected in series. For example, five "14s2p" Groups connected in
series could be described as a "5g14s2p" Stack. However, it is far more common to describe it as
a "70s2p" Stack.
Bank
A Bank is one or more stacks connected in parallel. For example, three "70s2p" Stacks connected
in parallel are referred to as a "3x70s2p" Bank.
Pack
A Pack is one or more Banks connected in series.
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3. System Overview
The Nuvation Energy High-Voltage BMS provides cell-level and stack-level control for battery stacks
up to 1250 VDC. The UL 1973 Recognized BMS modules in each stack ensure safe battery operation
and significantly reduce the effort of certifying the energy storage solution to meet UL 1973 and UL
9540. While the Stack Switchgear does not yet have UL 1973 recognition, it has been designed to
enable UL 1973 certification of the battery stack. For more information, please contact
[email protected]
Figure 1. High-Voltage BMS
A single Nuvation Energy Stack Switchgear unit manages each stack and connects it to the DC bus of
the energy storage system. The Nuvation Energy Stack Switchgear, is a pre-configured assembly that
incorporates the major functions of Nuvation Energy High-Voltage BMS into a rack-mountable unit
which includes stack monitoring, electrical disconnects, pre-charging, current sensing, fuses, and a
safety relay for E-Stop. It also includes supporting components like power supplies, indicator LEDs,
and external-facing connectors.
Cell Interface modules in each stack connect directly to battery cells to measure cell voltages and
temperatures and provide cell balancing.
The Stack Switchgear and Cell Interface modules operate together as a complete system called the
High-Voltage BMS. Available units/modules are listed below.
Table 1. Stack Switchgear and Cell Interface Modules
Model Unit/Module Name
NUVSSG-1250-100 Stack Switchgear, 1250 V, 100 A
NUVSSG-1250-200 Stack Switchgear, 1250 V, 200 A
NUVSSG-1250-300 Stack Switchgear, 1250 V, 300 A
NUV100-CI-12-1 Cell Interface - 12 channel
NUV100-CI-16-1 Cell Interface - 16 channel
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Model Unit/Module Name
NUV100-CI-4M12-1 Cell Interface - 12V 4 channel
Generally, a single battery stack uses one Stack Switchgear and one or more Cell Interface modules.
A breakdown of a single battery stack is shown in Figure 2
Figure 2. High-Voltage BMS single system diagram
In a multi-stack High-Voltage BMS configuration, as shown in Figure 3, each Stack Switchgear unit is
responsible for monitoring the state and safety of one battery stack. All Stack Switchgear units
connected to a single common DC bus in the system may be managed by a single Nuvation Energy
Battery Control Panel, where an Operator Interface provides a unified view and central control of the
multi-stack system.
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Figure 3. High-Voltage BMS multi-stack diagram
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3.1. Stack Switchgear
There are 3 variants of the Stack Switchgear:
▪The NUVSSG-1250-100 (1250 V, 100 A)
▪The NUVSSG-1250-200 (1250 V, 200 A)
▪The NUVSSG-1250-300 (1250 V, 300 A)
The high-level system design of Stack Switchgear is shown in Figure 2. Within a battery stack, the
Stack Switchgear connects to the daisy-chained Nuvation Energy Cell Interface modules. The Cell
Interface modules convert cell voltage and temperature measurements to digital values to be relayed
to the Stack Switchgear, and enable or disable cell balancing as required. Daisy-chaining the Cell
Interface modules facilitates the design of flexible and scalable battery energy storage systems.
The Stack Switchgear has high-voltage, high-current connectors that are accessible on the front of
the unit. These connect the battery stack to the rest of the system, which is typically a common DC
bus. Safety precautions are required to handle and connect cables into this unit.
Figure 4. Nuvation Energy Stack Switchgear Unit
The external interfaces to this unit are:
▪Battery Stack and DC Bus connectors
▪10/100 Base-T Ethernet RJ45 jack (Modbus-TCP)
▪Link Bus connector
▪E-stop connector
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▪Fan control connectors with breaker switch
▪Power In connector with breaker switch
▪Status LEDs (Power, Activity, and Fault)
▪Earth bonding connection (grounding stud)
3.2. Features
The Nuvation Energy Stack Switchgear internally includes the following major hardware components:
▪Nuvation Energy High-Voltage Stack Controller
▪Nuvation Energy High-Voltage Power Interface
▪Current measuring shunt
▪Three high-voltage DC contactors
▪Pre-charge circuit
▪Two fuses (short-circuit protection)
▪Safety relay (for E-Stop)
The following subsections describe the components in more detail.
3.2.1. Stack Controller and Power Interface
The Stack Switchgear contains a single Nuvation Energy High-Voltage Stack Controller and Nuvation
Energy High-Voltage Power Interface.
The Stack Controller has a central MCU which handles processes and decision-making required by the
battery management system. The Power Interface contains a redundant MCU to handle processes and
decision-making required to control the high-current contactors.
The Stack Controller and Power Interface are UL-recognized components, for use in UL 1973
stationary battery energy storage systems. For more information on the capabilities of the Stack
Controller and Power Interface please refer to the datasheets available online at
https://www.nuvationenergy.com/technical-resources.
3.2.2. Current Measuring Shunt
A precision current shunt in series with the negative side of the stack is used to measure the stack
charging/discharging current. Current measurement is performed by the Power Interface.
3.2.3. DC Contactors
High-voltage contactors are used by the BMS to connect the battery stack to the DC bus. There are
contactors on both the positive and negative sides of the stack. Nuvation Energy BMS opens the
contactors either by request of an external controller or in fault conditions. A third high-voltage
contactor is used in the pre-charge circuit (see Section 3.2.4).
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Contactors with auxiliary switch feedback are used so the BMS can raise a fault when it detects
contactor failure during opening or closing. Note that the expected lifespan of a contactor is impacted
significantly each time it connects or disconnects under load.
3.2.4. Pre-Charge Circuit
The Stack Switchgear has a pre-charge circuit to ensure safe connection of its battery stack to the DC
bus. The pre-charge circuit temporarily connects the stack to the DC bus through a power resistor.
This resistor allows a smaller current (proportional to the difference in voltage between the stack and
the DC bus) to flow between the stack and the DC bus. After a 5-second pre-charge timeout, if the
measured current is below a safe threshold, the BMS bypasses the pre-charge circuit by connecting
the stack directly to the DC bus.
This ensures the battery stack will not connect to the DC bus when an unsafe voltage mismatch is
present. By default, the Stack Switchgear is configured with a 150 Ω, 300 W power resistor, suitable
for a DC bus capacitance of 15 mF at 1000 V and 10 mF at 1250 V. As a custom request, the pre-
charge resistor can be sized specific to the end application.
3.2.5. Fuses
Inline fuses are used on both the positive and negative connections and are sized according to the
Stack Switchgear variant. See Table 2 for the fuse ratings for each Stack Switchgear variant.
The fuses interrupt a short circuit event; two of them are used to provide redundancy and to permit
use of the Stack Switchgear with an ungrounded battery stack. A microswitch is used on each fuse so
that the BMS can recognize blown fuses and issue a fault alert.
Table 2. Internal fuse ratings
Stack Switchgear Variant Fuse Rating Interrupt Current Rating
1250 V DC, 100 A 200 A 100 kA
1250 V DC, 200 A 315 A 100 kA
1250 V DC, 300 A 450 A 100 kA
3.2.6. Safety Relay (for E-Stop)
The Stack Switchgear has an internal safety relay for monitoring an external E-Stop signal. A safety
relay is used to ensure the relay cannot fail shorted.
This relay meets the requirements of the following standards: EN 954-1, EN 60204-1, VDE 0113-1
and IEC 60204-1. It also has approvals from UL, cUL, CCC and TUV. For more information about the
E-Stop functionality, see Section 4.2.6.
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3.3. Cell Interface
The Nuvation Energy Cell Interface is the direct link between the individual battery stack cells and the
rest of the battery management system. It facilitates battery monitoring and balancing
functionalities.
In a stack managed by the Stack Switchgear, one or more Cell Interface modules are used to convert
and relay cell voltage and temperature measurements digitally to the Stack Switchgear. When using
multiple Cell Interface modules, the same Cell Interface variant must be used—i.e. all NUV100-CI-12-
1, or all NUV100-CI-16-1, or all NUV100-CI-4M12-1. The firmware does not support a mixed chain of
different Cell Interface variants.
The following are variants of the Nuvation Energy Cell Interface:
▪The NUV100-CI-12-1, Cell Interface - 12 channel can monitor up to 12 series-connected cells
▪The NUV100-CI-16-1, Cell Interface - 16 channel can monitor up to 16 series-connected cells
▪The NUV100-CI-4M12-1, Cell Interface - 12V 4 channel can monitor up to 4 series-connected 12V
lead-acid cells. Note that cell balancing is not supported in Cell Interface - 12V 4 channel.
Figure 5. Nuvation Energy Cell Interface Module
The external interfaces to this module are:
▪Battery cells connector
▪Temperature sensors connector
▪2 Link Bus connectors
▪2 Indicator LEDs
The Cell Interface connects to the battery stack-referenced signals through high
voltage rated connectors. Safety precautions are required to handle and connect
cables into this module.
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4. Installation Instructions
During all stages of the installation, appropriate Personal Protective Equipment (PPE)
must be worn. This is especially critical when working with live voltages.
4.1. Stack Switchgear Mechanical Installation
4.1.1. Dimensions and Weight
The Stack Switchgear is 4U (rack-units) tall.
The unit weighs 23 kg [50.7 lbs].
Figure 6. Stack Switchgear Dimensions
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4.1.2. Installation Location and Position
The Stack Switchgear is rated to operate in the temperature range of 10 °C to 40 °C. It designed for
indoor applications.
The Stack Switchgear is primarily designed to fit in a standard 19" rack with a 23"-deep cabinet.
However, other mounting possibilities are supported, as the following subsections discuss. Depending
on the desired application, brackets can be ordered with part numbers listed in Stack Switchgear
Ordering Information.
4.1.2.1. Mounting Clearances
To maintain safe operating temperatures, it is recommended to leave 1U of space above the unit for
airflow. Depending on the environment, airflow, and ambient temperature, some installations may
require additional clearance above the unit.
4.1.3. Mounting Instructions
For rack and shelf options, the installation can be done by one person. For 2-post options, the
installation requires a minimum of two people.
Fasteners for attaching the brackets to the Stack Switchgear unit (M5 x 8 mm) are included with any
mounting bracket order. If fasteners other than the provided hardware is used, the screws cannot
extend into the Stack Switchgear more than 8 mm. High-voltage and high-power elements that exist
inside the unit could arc to the screw if it intrudes too deep into the unit.
Fasteners for attaching the brackets to the end desired surface are not provided, due to the
application-specific nature. In order to source these fasteners however, note that the corresponding
bracket slots have widths of 6.35 mm.
After removing the Stack Switchgear from its packaging, perform the following steps based on the
mounting brackets purchased.
4.1.3.1. Front-securing Rack-Mount, 19"

Third-party side-support angle brackets are necessary to uphold the weight of the
unit, in this mounting application.
Some examples include RASA22BK3 or RAAB2436BK products by Hammond
Manufacturing (https://www.hammfg.com/).
For front-securing 19" rack installations (i.e. using the NUVP-SSG-RB-19)
1. Install the side-support angle brackets (not included) on the rack at the desired location.
2. Install the brackets on the Stack Switchgear.
3. Place the Stack Switchgear onto the installed side-support angle brackets.
4. Secure the Stack Switchgear to the rail of the rack using the brackets installed.
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Figure 7. Rack-mount, 19", front-securing
4.1.3.2. 2-Post Rack-Mount, 19" And 23"
For 2-post rack installations (i.e. using the NUVP-SSG-RB-19-2P or NUVP-SSG-RB-23-2P)
1. Install one pair of brackets (i.e. both front or both rear brackets) on the posts at the desired
location.
2. Install the other pair of brackets on the Stack Switchgear.
3. Have one person support the Stack Switchgear in the desired position.
4. Attach the Stack Switchgear (with brackets installed) to the posts.
Figure 8. Rack-mount, 2-post, 19"
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Figure 9. Rack-mount, 2-post, 23"
4.1.3.3. Shelf-Mount
For shelf installations (i.e. using the NUVP-SSG-SB)
1. Install the brackets on the Stack Switchgear.
2. Place the Stack Switchgear on the shelf at the desired location.
3. Attach the Stack Switchgear (with brackets installed) to the shelf.
Figure 10. Shelf-mount
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4.2. Stack Switchgear Electrical Connections
Before making any connections, ensure that the service disconnect in Figure 11 is in
the OFF position.

The Stack Switchgear is configured for a specific battery topology based on the
details provided to Nuvation Energy during order fulfillment. Failure to use the same
number of Cell Interface modules and/or using a different battery topology will result
in undesirable Stack Switchgear behavior.
+ Please contact [email protected] if there is a change in the system
design that would require a Stack Switchgear configuration update.
4.2.1. Getting Started
▪Step 1: Ensure system is de-energized
▪Step 2: Ground the Stack Switchgear
▪Step 3: Connect Power In
▪Step 4: Connect Fan Control
▪Step 5: Connect E-Stop
▪Step 6: Connect to external PC
▪Step 7: Connect Cell Interface Link bus
▪Step 8: Connect Battery Stack and DC Bus
Below is a overview image of the external interfaces available on the front of the Stack Switchgear.
Figure 11. Stack Switchgear external interfaces
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4.2.2. Ensure system is de-energized
Ensure that the service disconnect switch, input power breaker, and the fan power breaker are in the
OFF position.
Service Disconnect
The manual service disconnect switch is accessible on the front of the Stack Switchgear. Use the
lock-out/tag-out to ensure that the battery stack does not connect to the DC bus or power
conversion system during installation.
Ensure the service disconnect switch is in the OFF position and lock-out/tag-out the switch.
Figure 12. Service Disconnect

The service disconnect switch removes power to the internal contactors—it does not
physically break the connection (this is done by the contactors themselves).
In the event of damage to the internal contactors (i.e. a welded contactor), the
service disconnect switch cannot guarantee that the DC bus has been disconnected
from the battery. It is therefore recommended to check for voltage present on the
Battery Stack and DC Bus terminals with a voltmeter before working on the stack to
ensure the contactors have opened fully.
Fan Power
An inline breaker provides the ability to turn off fan control for the Stack Switchgear. Ensure the
breaker is in the OFF position.
Figure 13. Fan Power Breaker
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