Fan Compatibility
The Nimbus is compatible with many PSC (Permanent Split Capacitor) and shaded pole motors. The Nimbus is not compatible with capacitor start motors. Confirm TRIAC controllability with the motor manufacturer before installation or contact CRI customer service for testing recommendations. Attempting to control a fan that is not compatible could cause excessive heating and could permanently damage the fan motor.
Control Accuracy and Hysteresis
The standard Nimbus is accurate to within ±1.5˚C in the temperature control mode and ±0.4VDC, ±0.8mA in the control signal mode. If your application requires greater accuracy, contact customer service. For most single-phase AC fans, there is direct correlation between fan speed and voltage. For some fans however, this will not be the case. To prevent fans (using fan ON/OFF feature) and alarms from cycling on and off, a certain amount of hysteresis has been built in to the Nimbus. That is, fans will shut off 2-3% below the set point and turn back on 2-3% above the set point. Alarms will turn on at the set point and turn off 1-2°C below or 5% above the set point.
Voltage Loss
For a typical fan, expect a voltage drop to the fan of about 2-4% at full voltage.
Changing Control Settings
With the exception of the “fixed speed mode”, the Nimbus will not recognize any changes in switch or jumper settings made with power applied. Power must be turned OFF before changing any switch or jumper settings.
Minimum Fan Currents
Fans may not control properly if the total fan current is less than the minimum published current, see table 1.
Maximum Fan Currents
Some motors draw higher current at less than maximum voltage. Contact motor manufacturer for details.
Start Pulse
Some fans that run just fine at lower voltages will not start at these voltages; therefore the Nimbus will start fans at full voltage for 2 seconds before throttling back to the appropriate control speed.
EMI
The amount of electrical noise emitted by the Nimbus increases as fan speed decreases. The amount of noise emitted is fan dependant. If the electrical noise is an issue, an AC Input Line Filter can be used. CRI recommends the following line filters from www.filterconcepts.com or equivalent.
| Emissions class |
0-3A load |
0-7A load |
| EN55011, class A |
Not required |
Not required |
| EN55011, class B |
LE5 |
LE10 |
| FCC 47CFR part 15, class B |
LX3 |
LX10 |
Current Derating
The Nimbus may be run above 40˚C. However, the maximum current ratings will decline according the chart below.
Figure
10
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Specifications:
- Power Source: 95 - 250 VAC
- Frequency: 47 - 64 Hz
- Current Ratings: see table 1
- Storage Temperature: -40°C to 125°C
- Operating Temperature: -25° to 70°C
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