All about Kohler controllers

LOAD MANAGEMENT

Load management allows you to prioritize loads and remove noncritical loads when the power supply becomes unable to support the entire demand.

Each load is assigned a priority level. Load management determines when priority levels are signaled to disconnect (shed) and reconnect (add). When multiple generators are online, load management matches the load to the generator capacity.

The system can control feeder breakers or transfer switches. Dry contacts or communications can be provided to interface with your building-management system.

In a paralleled generator system, it is imperative to plan for the unlikely event of a generator failure. Removing or shedding load prevents the remaining online generators from overloading and tripping offline.

Load Add

Loads can be added based on several considerations, including:

• Generator bus capacity: loads are added based on the kW capacity of the bus and an assumed kW demand of the load.
• kW overload: When the generators reach their overload setpoints, low-priority loads sequentially shed until the load falls below the overload setpoint.
• Number of generators online: loads are added based on how many generators are connected to the bus; this is most effective in systems with same-size generators.

Load Shed

A load-shed event can be triggered by several causes, including:

• Generator failure: Loads are shed based on the number of failed generator sets.
• Underfrequency: This is often an indication that the generators are fully loaded and cannot supply additional power to the load. When the bus frequency reaches its underfrequency setpoint, preset loads are shed.

GENERATOR MANAGEMENT

Generator management optimizes the number of online generators based on the load’s kW demand, starting and stopping them as required. Generators are sequenced on in order of operator-assigned priority (or based on runtime) and taken off in reverse priority. Operator-defined setpoints determine the load level percentage and time delay at which the genset will be brought on or taken offline.

VOLTAGE REGULATION

Voltage regulation helps to minimize voltage fluctuations and quickly stabilize the system when equipment is added or removed. A common experience of voltage fluctuation is when a piece of equipment is turned on and the lights dim or a fan slows down for a moment. While not detrimental to most commercial and industrial equipment, these fluctuations can be distracting.

Generator voltage can be affected by both engine speed and current, and it can be adjusted either manually or through software. Controllers are responsible for detecting and quickly responding to voltage fluctuations, typically maintaining a range between 0.25% and 0.50%.

NFPA 110

NFPA 110 is the National Fire Protection Association’s performance standard for emergency and standby power systems. An individual product cannot be marked as NFPA 110-compliant; the overall power system must be installed, maintained, tested, and operated per the NFPA standard to be compliant. Kohler is committed to designing emergency and standby power components with features that ensure the power system’s compliance with NFPA 110.

NFPA 110 has identified two levels of requirements that pertain to the installation, performance, and maintenance of the power system:

• Level 1 pertains to power systems where failure to perform could result in loss of life or serious injury.
• Level 2 pertains to power systems where failure to perform is less critical to human life and safety.

The installation, performance, and maintenance requirements associated with a power system depend upon the power system level.

KOHLER® controllers are designed to meet the requirements of NFPA 110. Key features include:

• Emergency stop.
• Master switch including Stop/Run/Auto controls.
• Audible horn, visual warnings, and visual fault indicators.
• System faults and status monitored and annunciated on both the controller display and remote annunciator.

PROGRAMMABLE I/O

Every job is unique and using a controller that allows for customization to support your needs is critical. Controllers offer programmable inputs and outputs to help with the customization.

Inputs are external signals the controller receives from various connected monitoring and management systems, which the controller can then process and respond to based on its programming. Likewise, outputs are information about the generator and/or automatic transfer switch operating conditions that the controller provides to external systems.

• Analog Inputs and Outputs: These are typically used for sensors that show varying amounts of a given metric, such as fuel level in a diesel tank. Analog inputs and outputs identify a system state within a range of values, typically from 0% to 100%.
• Digital Inputs and Outputs: These are used for sensors that show a high or low state, such as an alarm, which is either active or inactive. As an example, a power system can be programmed to trigger a remote shutdown when an input reports a high state.