Emerson EV3 Series, Application Manuallines

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12 AGL_Sol_EV3_E_Rev_01
The power demand must be written in register [102]. The value represents the percentage of power
(0%-100%). The maximum power that can be commanded on the stator is readable via register [52].
The relation between the power and the value introduced in register [102] is the following:
▪
If the value is a multiple of 10:
𝑃𝑜𝑤𝑒𝑟~150 × (
[102]
100
)
▪
If the value is not a multiple of 10:
𝑃𝑜𝑤𝑒𝑟 ~ 150 ×
([102] 𝑑𝑖𝑣 10 + 1) × 10
100
(Stator Heating Demand = value stored in register [102])
The power commanded on the stator is interpreted by the drive according to Table 12 :
User demand Drive received
1 - 10% 10%
11 - 20% 20%
21 - 30% 30%
31 - 40% 40%
… …
81 - 90% 90%
91 - 100% 100%
Table 12: User commanded power
4.4 Envelope control
The drive offers 4 different envelope control modes allowing the compressor to operate at four
different safety levels within the dedicated envelopes. Two conceptually different methods are
provided to achieve this:
▪
Passive Envelope Control (modes 0, 1, 2) which is based on the internal current/speed curve
of the drive;
▪
Active Envelope Control (mode 3) which takes actions based on the evaporating and
condensing temperatures/pressures received from the system controller via Modbus.
The 4 modes can be selected from a list through register [231]:
o
0: Full Envelope Protection
o
1: High-Speed Envelope Protection
o
2: Advanced Speed-Drop Protection Mode
o
3: Active Envelope Protection
4.4.1 Passive Envelope Protection
The passive envelope control implies the so-called Overload Protection. Based on the compressor
operation envelope, which is transferred in a speed-current curve, the drive will compute and adjust
frequently the output current threshold. Once the output current exceeds this calculated threshold
the drive will go in the Speed-Drop Protection (SDP) mode, ie, a kind of power limitation to protect
the drive and the stator windings against overload. The difference between the three modes from the
user’s point of view, consists in the access to different speed ranges and the speed at which the
drive folds back in case of speed-drop protection:
0: Full Envelope Protection
▪
Overload Protection enabled.
▪
Normal Operation Mode: the minimum speed is the speed available for the whole envelope.
Taken from the EEPROM and stored in register [109].
▪
SDP mode: the speed at which the drive drops is the same as the minimum speed from the
Normal Operation mode.
▪
In this mode the user provides only the speed demand.