Motors
Overview
The motor tag is paired with the equip tag to model equipment that operates with an electric motor. Haystack defines the following entities that use motors:
Often these motors are driven by a variable frequency drive, or VFD, that exposes many points. If a motor uses a VFD, then it should also be tagged with the vfd marker. Typically, motors such as fans and pumps are sub-components of a larger piece of equip that we nest via the equipRef tag.
Points
Standardized points for equip are extended to motors as follows:
- MotorEnableCmd: command that permits or prohibits a motor to operate
- MotorRunCmd: commands a motor to run or stop running
- MotorRunSensor: senses the on/off state of a motor
- alarm sensor: boolean alarm condition
Permission from MotorEnableCmd may be required for MotorRunCmd to take effect.
If the motor is driven by a Variable Frequency Drive (VFD), then it should be tagged with the vfd marker.
Points related to motor speed control:
- MotorSpeedModulatingCmd: command for modulating motor speed
- VfdOutputElecAcFreqCmd: command for a VFD's output AC electric frequency
- MotorSpeedModulatingSensor: sensor for modulating motor speed
- VfdOutputElecAcFreqSensor: sensor for a VFD's output AC electric frequency
Modulating speed is defined as a percentage where 0% is off and 100% is full speed.
Many VFDs will also provide many of the same points as an electric meter. Measurements such as electric demand, consumption, voltage, and current should follow the same conventions as elec meters.
Fans
Fans may optionally be defined as either an equip or a point. If the fan motor is driven by a VFD, then it is recommended to make the fan a sub-equip. However in many cases a simple fan in a terminal unit such as a vav is more easily modeled as just a point.
Fan Points
Standardized points for motors are extended to fans as follows:
- FanEnableCmd: command that permits or prohibits a fan to operate
- FanRunCmd: commands a fan to run or stop running
- FanRunSensor: senses the on/off state of a fan
- FanSpeedModulatingCmd: command for modulating fan speed
Modulating speed is defined as a percentage where 0% is off and 100% is full speed.
Permission from FanEnableCmd may be required for FanRunCmd to take effect.
Fan Equips
When the fan motor is a VFD, it should be modeled as an equip entity using the standard VFD points described above. If you wish to standardize modeling all fans as equip, then simple single speed fans should define their state via a run point.
Example of a VFD fan on an AHU:
id:@ahu ahu equip
id:@ahu-fan equipRef:@ahu discharge fan vfd motor equip
id:@ahu-fan-run equipRef:@ahu-fan discharge fan run cmd point
id:@ahu-fan-status equipRef:@ahu-fan discharge fan run status point
id:@ahu-fan-speed equipRef:@ahu-fan discharge fan drive speed cmd unit:"%" point
Note that the fan is modeled as an sub-equip of the AHU via the equipRef
tag. The VFD points are defined under the fan itself, however we must
flatten the discharge and fan tags into the points.
Pumps
Pumps may optionally be defined as either an equip or a point. If the pump is a VFD, then it is recommended to make it an equip level entity. However, if the pump is modeled as a simple on/off point as a component within a large piece of equipment such as a boiler, then it is modeled as just a point. Pumps should follow the same point and equip level modeling conventions as fans.