Toshiba MMU-AP0091H service manual Ipdu

No.	Item	Operation explanation and applied data, etc.	Remarks
10	Compressor	Each compressor is stopped should the Pd pressure sensor reach a
	stop due to	value of 3.5 MPa. This control is performed by the header unit and
	high pressure	any follower units.
	release
11	Case heater	Heating is provided for both the compressor case and accumulator.
	control	When the compressor in any outdoor unit is stopped, the heater is
		switched on to prevent accumulation of refrigerant.
		After installation of a system, it should be powered for the specified
		period of time prior to operating a test run to prevent damage to the
		system.
		If the system has not been powered for a prolonged period of time, it
		is important to apply power for the specified period of time before
		resuming operation.
		This function is often performed in conjunction with the compressor
		winding heating control. When this occurs, a noise may be heard
		which is not an indication of a malfunction.
		(1) Contents of control
		• The function is performed during when the compressor is off.
		• When the TO sensor temp measures 28°C or higher the heater
		turns off and turns on when it change:measures 25°C or lower
		• The heater remains ‘ON’ for 10 minutes after the compressor
		has changed mode from Off to On.
12	IPDU control	The IPDU controls the inverter compressor by communicating a
		command frequency that controls the compressor speed, depending
		on any active releases.
		The main controls of the IPDU P.C. board are:
		(1) Current release control
		Feedback from the AC input current sensor (CT) is used to
		prevent the inverter input current exceeding its specified limit
		(2) Heat sink temperature detection control
		• Feedback from the thermistor (TH) on the compressor driving	• A TH sensor is
		module is used to prevent the IGBT from overheating. The	provided in each two
		highest value is taken from IPDU 1 and IPDU 2 TH sensors.	IPDU.
		(3) Over-current protective control
		• When an over-current condition is detected by the IPDU, the
		compressor is stopped.
		(4) Compressor case thermo control
		• The compressor stops when the compressor case thermostat is
		activated.
		• Whenever this condition occurs, a 1 count is added to the	• The case thermostat
		system error count.	is normally closed
		• After a period of 2 minutes and 30 seconds, the compressor is	and connected to
		reactivated and the error count cleared if the operation contin-	interface P.C. board.
		ues without further error for a period of 10 minutes or more.
		• If the error count reaches 4, the check code [H04] is displayed
		(for compressor 1) and [H14] (for compressor 2).
13	High pressure	(1) High pressure SW control
	prevention	• The high pressure switch is connected to the IPDU board and is
	control	in the normally closed condition.
		• When the high pressure switch is activated, the compressor is
		stopped.
		• Whenever this condition occurs, a 1 count is added to the
		system error count.
		• After a period of 2 minutes and 30 seconds, the drive to the
		compressor is reactivated and the error count is cleared if the
		operation continues with further error for a period of 10 minutes
		or more.
		• If the error count reaches 4, the check code [P04] is displayed.

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